George Mason University General Chemistry 211 Chapter 6 Thermochemistry: Energy Flow and Chemical Change

Size: px
Start display at page:

Download "George Mason University General Chemistry 211 Chapter 6 Thermochemistry: Energy Flow and Chemical Change"

Transcription

1 George Mason University General Chemistry 211 Chapter 6 Thermochemistry: Energy Flow and Chemical Change Acknowledgements Course Text: Chemistry: the Molecular Nature of Matter and Change, 7 th edition, 2011, McGraw-Hill Martin S. Silberberg & Patricia Amateis The Chemistry 211/212 General Chemistry courses taught at George Mason are intended for those students enrolled in a science /engineering oriented curricula, with particular emphasis on chemistry, biochemistry, and biology The material on these slides is taken primarily from the course text but the instructor has modified, condensed, or otherwise reorganized selected material. Additional material from other sources may also be included. Interpretation of course material to clarify concepts and solutions to problems is the sole responsibility of this instructor. 1/13/2015 1

2 Thermochemistry Whenever matter changes composition, such as in a chemical reaction, the energy content of the matter changes also In some reactions the energy that the reactants contain is greater than the energy contained by the products This excess energy is released as heat In other reactions it is necessary to add energy (heat) before the reaction can proceed The energy contained by the products in these reactions is greater than the energy of the original reactants Physical changes can also involve a change in energy such as when ice melts 1/13/2015 2

3 Thermochemistry Thermodynamics is the science of the relationship between heat and other forms of energy Thermochemistry is the study of the quantity of heat absorbed or evolved by chemical reactions Energy is the potential or capacity to move matter (do work); energy is a property of matter Energy can be in many forms: Radiant Energy - Electromagnetic radiation Thermal Energy - Associated with random motion of a molecule or atom Chemical Energy - Energy stored within the structural limits of a molecule or atom 1/13/2015 3

4 Energy There are three broad concepts of energy: Kinetic Energy (E k ) is the energy associated with an object by virtue of its motion, E k = ½mv 2 Potential Energy (E p ) is the energy an object has by virtue of its position in a field of force, E p = mgh Internal Energy (E i or U i ) is the sum of the kinetic and potential energies of the particles making up a substance E (i) = E k + E p 1/13/2015 4

5 Energy SI (metric) unit of energy is the Joule: 1 watt = 1 J/s (J) = kg m 2 /s 2 1 cal = amount of energy needed to raise 1 g of water 1 o C (common energy unit) 1 cal = J 1 Btu = 1055 J (Btu - British Thermal Unit) The Law of Conservation of Energy: Energy may be converted from one form to another, but the total quantities of energy remain constant 1/13/2015 5

6 Practice Problem Thermal decomposition of 5.0 metric tons of limestone (CaCO 3 ) to Lime (CaO) and Carbon Dioxide (CO 2 ) requires 9.0 x 10 6 kj of heat (E) Convert this energy to: a. Joules b. calories c. British Thermal Units (Btu) (5 tons) CaCO (s) 9.0 x 10 6 kj CaO(s) CO (g) J 9 ΔE(J) 9.0 x 10 kj) 9.0 x 10 J 1kJ J 1 cal 9 9 ΔE(cal) 9.0 x 10 kj x x 10 cal 1 kj J J 1 Btu 6 6 ΔE(Btu) 9.0 x 10 kj x x 10 Btu 1 kj 1055 J 1/13/2015 6

7 Energy When a chemical system changes from reactants to products and the products are allowed to return to the starting temperature, the Internal Energy (E) has changed (E) The difference between the system internal energy after the change (E final ) and before the change (E initial ) is: E = E final - E initial = E products - E reactants If energy is lost to the surroundings, then E final < E initial E < 0 If energy is gained from the surroundings, then E final > E initial E > 0 1/13/2015 7

8 Heat of Reaction In chemical reactions, heat is often transferred from the system to its surroundings, or vice versa The substance or mixture of substances under study in which a change occurs is called the thermodynamic system (or simply system) The surroundings are everything in the vicinity of the thermodynamic system Heat is defined as the energy that flows into or out of a system because of a difference in temperature between the system and its surroundings Heat flows from a region of higher temperature to one of lower temperature Once the temperatures become equal, heat flow stops 1/13/2015 8

9 Heat of Reaction When heat (q) is released from the system (heat out) to the surroundings (q < 0 negative), the reaction is defined as an Exothermic reaction When the surroundings deliver heat (heat in) to the system (q > 0 positive), the reaction is defined as an Endothermic reaction Exothermic Endothermic q<0 q>0 Energy Surroundings Energy Surroundings System System 1/13/2015 9

10 Heat of Reaction Heat of a system is denoted by the symbol q The sign of q is positive (q > o) if heat is absorbed by the system, i.e., system temperature increases The sign of q is negative (q < o) if heat is evolved by the system, i.e., system temperature decreases Heat of Reaction (at a given temperature) is the value of q required to return a system to the given temperature when the reaction stops at the completion of the reaction 1/13/

11 Heat of Reaction Consider a chemical reaction that begins with the system and surroundings temperature at 25 o C If the temperature of a system decreases during the reaction, heat flows from the surroundings into the system When the reaction stops, heat continues to flow until the system temperature returns to the temperature of the surroundings at 25 o C Heat has been absorbed by or added to the system from the surroundings The value of q is positive, that is: q > 0 1/13/

12 Heat of Reaction If the temperature of the system rises, heat flows from the system to the surroundings When the reaction stops, heat continues to flow to the surroundings until the system returns to the temperature of its surroundings (at 25 o C) Heat has flowed out of the system; it has evolved (lost) heat; thus, q is negative, that is q < 0 1/13/

13 Heat Flow and Phase Changes Predict the sign of q for each of the processes below 1. H 2 O(g) H 2 O(l) Condensation - Energy (heat) is lost by water vapor Exothermic reaction - q is negative 2. CO 2 (s) CO 2 (g) Evaporation Energy (heat) is absorbed (added) by the system from its surroundings Endothermic reaction - (q is positive) 3. CH 4 (g) + O 2 (g) CO 2 (g) + H 2 O(g) Combustion Burning (oxidation) of Methane releases (evolves) heat to surroundings Exothermic reaction - (q is negative) 1/13/

14 Work & Internal Energy Internal Energy The Internal Energy of a system, E, is precisely defined as the heat at constant pressure (q p ) plus any work (w) done by the system Work is the energy transferred when an object is moved by a force w = - P Δ V = - P (V - V ) Internal Energy used ΔE = q p + w ΔE = q p + (-P ΔV) q p = ΔE + P ΔV final initial to expand volume by increasing pressure is lost to the surroundings, thus the negative sign Adiabatic Process Thermodynamic Process Without the Gain or Loss of Heat ( q = 0) 1/13/

15 Practice Problem A system delivers 225 J of heat to the surroundings while delivering 645 J of work. Calculate the change in the internal energy, E, of the system q p = heat delivered to surroundings from system = J w = work delivered to surroundings from system = J ΔE = change in internal energy ΔE = q p + w ΔE = J + (-645 J) = J Heat is lost to the surroundings 1/13/

16 Pressure-Volume Work Sign conventions for q, w, and E: q + w (-P V) = E Depends on sizes of q and w + Depends on sizes of q and w q: + system gains heat q: system loses heat w: + work done on system w: work done by system 1/13/

17 Practice Problem A system expands in volume from 2.00 L to 24.5 L at constant temperature. Calculate the work (w), in Joules (J), if the expansion occurs against a constant pressure of 5.00 atm w = - pδv kg Pa m s 10 m w = atm (24.5 L L) atm Pa L kg m kg m 1J w = -1, = s s kg m 2 s 4 w = J /13/

18 Practice Problem A system that does no work but which transfers heat to the surrounding has: a. q < 0, E > 0 b. q < 0, E < 0 c. q > 0, E > 0 d. q > 0, E < 0 e. q < 0, E = 0 A system that does no work but receives heat from the surroundings has: a. q < 0, E > 0 b. q > 0, E < 0 c. q = E d. q = - E e. w = E A system which undergoes an adiabatic change (i.e., q = 0) and does work on the surroundings has: a. w < 0, E = 0, b. w > 0, E > 0 c. w > 0, E < 0 d. w < 0, E > 0 e. w < 0, E < 0 A system which undergoes an adiabatic change (i.e., q = 0) and has work done on it by the surroundings has: a. w = E b. w = - E c. w > 0, E < 0 d. w < 0, E > 0 e. w > E 1/13/

19 Enthalpy and Enthalpy Change Enthalpy, denoted H, is an extensive property of a substance that can be used to obtain the heat absorbed or evolved in a chemical reaction An extensive property is one that depends on the quantity of substance Enthalpy is a state function, a property of a system that depends only on its present state and is independent of any previous history of the system Enthalpy represents the heat energy tied up in chemical bonds 1/13/

20 Enthalpy and Enthalpy Change The change in Enthalpy for a reaction at a given temperature and pressure, called the Enthalpy of Reaction, is obtained by subtracting the Enthalpy of the reactants from the Enthalpy of the products. ΔH = H - H rxn (products) (reactants) 1/13/

21 Enthalpy and Enthalpy Change Enthalpy is defined as the internal energy plus the product of the pressure and volume (work) H E PV The change in Enthalpy is the change in internal energy plus the product of constant pressure and the change in Volume ΔH = ΔE + P ΔV 1/13/

22 Recall: Enthalpy and Enthalpy Change q = ΔE + P ΔV p ΔH = ΔE + P ΔV Thus : ΔH = q p (At Constant Pressure) The change in Enthalpy equals the heat gained or lost (heat of reaction, H rxn ) at constant pressure This represents the entire change in internal energy (E) minus any expansion work done by the system (PV would have negative sign) 1/13/

23 Practice Problem An ideal gas (the system) is contained in a flexible balloon at a pressure of 1 atm and is initially at a temperature of 20.0 o C. The surrounding air is at the same pressure, but its temperature is 25 o C. When the system is equilibrated with its surroundings, both systems and surroundings are at 25 o C and 1 atm. In changing from the initial to the final state, which of the following relationships regarding the system is correct? a. E = 0 b. E < 0 c. H = 0 d. w > 0 e. q > 0 Heat is added, internal energy increases Heat is added, internal energy increases E increases and P V work is done by system P V work is done by system (volume increase) Temperature (heat) in system increases E > 0 E > 0 H > 0 W < 0 1/13/

24 Practice Problem In which of the following processes is H = E, i.e. P V = 0? a. 2HI(g) H 2 (g) + I 2 (g) at atmospheric pressure (P V = 0 no change in moles, volume) b. Two moles of Ammonia gas are cooled from 325 o C to 300 o C at 1.2 atm (P V 0 Vol decreases) c. H 2 O(l) H 2 O(g) at 100 o C at atmospheric pressure (P V 0 Vol increases) d. CaCO 3 (s) CaO(s) + CO 2 (g) at 800 o C at atmospheric pressure (P V 0 Vol increases) e. CO 2 (s) CO 2 (g) at atmospheric pressure (P V 0 Vol increases) 1/13/

25 Comparing E & H Reactions that do not involve gases Reactions such as precipitation, acid-base, many redox, etc., do not produce gases Since the change in volumes of liquids and solids are quite small: V 0 P V 0 H E Reactions in which the amount (mol) of gas does not change (Vol of Gaseous Reactants = Vol Gaseous Products V = 0 P V = 0 H = E Reactions in which the amount (mol) of gas does change PV 0 However, q p is usually much greater than PV Therefore: H E 1/13/

26 Example: Comparing E & H 2H 2 (g) + O 2 (g) 2H 2 O(g) Change in moles: 3 mol 2 mol PV 0 H = kj and PV = -2.5kJ E = H - PV = kj - (-2.5 kj) = kj Most of E occurs as Heat (H = q p ) H E For many reactions, even when PV 0, H is close to E 1/13/

27 Comparing E & H For which one of the following reactions will H be approximately (or exactly) equal to E? a. H 2 (g) + Br 2 (g) 2HBr(g) (No change in volume; no change in work, PV = 0) b. H 2 O(l) H 2 O(g) (Change in volume; change in work due to gas expansion, PV 0) c. CaCO 3 (s) CaO(s) + CO 2 (g) (Change in volume; change in work due to gas expansion, PV 0 d. 2H(g) + O(g) H 2 O(l) (Change in volume; condensation, heat (q) released, PV 0) e. CH 4 (g) + 2O 2 (g) CO 2 (g) + 2H 2 O(l) (Change in volume; condensation, heat (q) released, PV 0) 1/13/

28 Exothermic and Endothermic Processes Energy (E), Pressure (P), and Volume (V) are state functions Enthalpy (H) is also a state function, which means that H depends only on the difference between H final & H initial The Enthalpy change of a reaction, also called the Heat of Reaction (H rxn ), always refers to H rxn = H final - H initial = H products - H reactants H products can be either more or less than H reactants The resulting sign of H indicates whether heat is absorbed from the surroundings (heat in) or released to the surroundings (heat out) in the process 1/13/

29 Exothermic and Endothermic Processes An Exothermic reaction releases heat (heat out) to surroundings with a decrease in system Enthalpy CH 4 (g) + 2O 2 CO 2 (g) + 2H 2 O(g) + heat Exothermic: H final < H initial H < 0 (negative) An Endothermic reaction absorbs heat (heat in) from the surroundings resulting in an increase in system Enthalpy Heat + H 2 O(s) H 2 O(l) Endothermic H final > H initial H > 0 (positive) 1/13/

30 Types of Enthalpy Changes When a compound is produced from its elements, the Enthalpy change (Heat of Reaction) is called: Heat of Formation ( H f ) K(s) + ½Br 2 ()l) KBr(s) H = H f When a substance melts, the Enthalpy change is called: Heat of Fusion ( H fus ) NaCl(s) NaCl(l) H = H (fus) When a substance vaporizes, the Enthalpy change is called: Heat of Vaporization C 6 H 6 (l) C 6 H 6 (g) H = H (vap) 1/13/

31 Thermochemical Equations A Thermochemical Equation is the chemical equation for a reaction (including phase labels) in which the equation is given a molar interpretation, and the Enthalpy of Reaction ( H rxn ) for these molar amounts is written directly after the equation. N (g) + 3 H (g) 2 NH (g) ΔH rxn = kj H is negative; heat is lost to surroundings 1 mol N mol H 2 yields 91.8 kj of heat Reaction is Exothermic 1/13/

32 Practice Problem Sulfur, S 8, burns in air to produce Sulfur Dioxide. The reaction evolves (releases) 9.31 kj of heat per gram of Sulfur at constant pressure. Write the thermochemical equation for this reaction. S O SO + Heat Exothermic Reaction Balance the Reaction S 8 8 O 2 8 SO 2 ΔH kj Exothermic Reaction 1/13/

33 Practice Problem In a phase change of water between the liquid and the gas phases, kj of energy was released by the system. What was the product, and how much of it was formed in the phase change. (Data: H 2 O(l) H 2 O(g) H = kj/mol) a. 315 g of water vapor was produced b g of water vapor was produced c mol of water vapor was produced d mol of liquid water was produced e g of liquid water was produced H is positive (endothermic reaction) Since energy was released, the gas condensed to liquid kj / kj / mol = 17.5 mols 1/13/

34 Thermochemical Equations The following are two important rules for manipulating Thermochemical equations: When a thermochemical equation is multiplied by any factor, the value of H for the new equation is obtained by multiplying the H in the original equation by that same factor When a chemical equation is reversed, the value of H is reversed in sign 1/13/

35 Practice Problem When White Phosphorus burns in air, it produces Phosphorus (V) Oxide (Change in Oxidation state) P 4 (s) + 5O 2 (g) P 4 O 10 (s) H = kj/mol What is H for the following equation? P 4 O 10 (s) P 4 (s) + 5O 2 (g) H =? Ans: The original reaction is reversed Change the Sign!! H = kj/mol 1/13/

36 Practice Problem Carbon Disulfide (CS 2 (l)) burns in air, producing Carbon Dioxide and Sulfur Dioxide CS 2 (l) + 3 O 2 (g) CO 2 (g) + 2 SO 2 (g) H = kj What is H for the following equation? 1/2 CS 2 (l) + 3/2 O 2 (g) 1/2 CO 2 (g) + SO 2 (g) Ans: The new reaction uses ½ the original amounts Divide H by 2 H = (-1077 / 2) = kj 1/13/

37 Applying Stoichiometry and Heats of Reactions Consider the reaction of Methane, CH 4, burning in the presence of Oxygen at constant pressure. Given the following equation, how much heat could be obtained by the combustion of 10.0 grams CH 4? o CH (g) + 2 O (g) CO (g) + 2 H O(l) ΔH = kj / mol mol CH kj 10.0 g CH g CH 1 mol CH = kj 4 4 1/13/

38 Measuring Heats of Reaction Heats of Reactions (Enthalpy change of reaction H rxn ) are determined from the heat required to raise the temperature of a substance A thermochemical measurement is based on the relationship between heat and temperature change; that is the quantity of heat (q) absorbed or released by an object is proportional to its temperature change Heat (q) ΔT or q = constant ΔT Each object has its own heat capacity, which is the quantity of heat required to change its temperature by 1 Kelvin (K) Thus, proportionality constant above is the Heat Capacity: q = Constant = Heat Capacity [in units of J / K] ΔT 1/13/

39 Measuring Heats of Reaction The specific heat capacity, S, (or specific heat ) is the heat required to raise the temperature of one gram of a substance by one degree Celsius S is in units of J/g o K m = grams of sample q = m S ΔT T = T final - T initial The molar heat capacity, C, of a sample of substance is the quantity of heat required to raise the temperature of one mole of substance one degree Celsius C is in units of J/mol o K, n = moles of substance q = n C ΔT T = T final - T initial 1/13/

40 Measuring Heats of Reaction Bomb Calorimeter used to measure heats of combustion 1/13/

41 Measuring Heats of Reaction Specific Heats and Molar Heat Capacities of some substances 1/13/

42 Practice Problem Suppose you mix 20.5 g of water at 66.2 o C with 45.4 g of water at 35.7 o C in an insulated cup. What is the maximum temperature of the solution after mixing? Ans: The heat lost by the water at 66.2 o C is balanced by the heat gained by the water at 35.7 o C o o q = m S ΔT m = 20.5 g 1 2 m 2 T f = T f m T f = T f T = 45.2 C ΔT 1 = T f C ΔT 2 = T f C m = 45.4 g -q = q = - m SΔT = m SΔT lost gained o o -m * T C = m * T C 1 f 2 f o 1/13/2015 f 42

43 Practice Problem A piece of copper with a temperature of 100 o C is dropped into a beaker containing 50.0 grams of water at 20 o C. When the reaction is completed the temperature of the solution is 25 o C. Assuming no loss of heat and the heat capacity of the solution is the same as water, J/(g * o K), what is the heat capacity of Copper in J/K? ΔT 1 = (25 100) = -75 o C ΔT 2 = (25 20) = 5 o C Heat change by increasing water temperature by 5 o K q 2 = 50g * J/(g * o K) * 5 o K = 1,046 J Heat lost by copper (q 1 ) is equal to heat gained by water -q 1 = +q 2 Therefore, The Heat Capacity of copper is: 2 q -q -1,045 J 1 = = o = 13.9 J / K ΔT -75 C 1/13/

44 Practice Problem How much heat is gained by Nickel when 500 g of Nickel is warmed from 22.4 o C to 58.4 C? [The specific heat of Nickel is J/(g C)] a J b J c J d J e J Ans: d q = m s ΔT f o o o i ΔT = T (58.4 C) - T (22.4 C) = 36.0 C o s = Specific Heat Nickel = J / g C m = 500 g q = 500 g * J / g C * 36.0 C q = 7992 = 8000 J 1/13/ o o

45 Practice Problem When 25.0 ml of 0.5 M H 2 SO 4 is added to 25.0 ml of 1.00 M KOH in a calorimeter at 23.5 o C, the temperature rises to o C Calculate H rxn for each reactant. Assume density (d) and specific heat of the solution (s) are the same as water 2 KOH(aq) + H2SO 4(aq) K 2SO 4(aq) + 2 H2O(l) q = m s ΔT (Δ T = T - T ) d = 1 g / ml s = J / g C soln f i 1.00 g J o 1 kj q soln = mL o C = kj ml g C 1000 J Calculate moles mol H SO 1 L 25.0 ml = mol H SO L 1000 ml 1.00 mol KOH 1 L 25.0 ml = mol KOH L 1000 ml Both KOH or H SO are limiting (2 moles KOH / 1 mol H SO ) Con t 1/13/ o

46 Practice Problem (Con t) When 25.0 ml of 0.5 M H 2 SO 4 is added to 25.0 ml of 1.00 M KOH in a calorimeter at 23.5 o C, the temperature rises to o C. Calculate H rxn for each reactant. Assume density (d) and specific heat of the solution are the same as water. Temperature of water increased (23.5 o C o C) The Reaction is Exothermic (heat released to surroundings (water)) Thus, q rxn is negative q = q = kj soln rxn kj H (H SO ) kj / mol H SO rxn mol H2SO kj H rxn (KOH) kj / mol KOH mol KOH 1/13/

47 Hess s Law Hess s law of Heat Summation For a chemical equation that can be written as the sum of two or more steps, the Enthalpy change for the overall equation is the sum of the Enthalpy changes for the individual steps In coupled reactions, the Enthalpy change for the overall reaction is the sum of the Enthalpy changes for the coupled reactions Note: It is often necessary to reverse chemical equations to couple them so chemical species are on the correct side of yield sign, or multiply through by a coefficient to cancel common chemical species 1/13/

48 Hess s Law For example, suppose you are given the following data: o S(s) + O (g) SO (g) ΔH = -297 kj / mol 2 2 o 2 SO (g) 2 SO (g) + O (g) ΔH = 198 kj / mol Could you use these data to obtain the Enthalpy change for the following reaction? o 2 S(s) + 3 O (g) 2 SO (g) ΔH =? 2 3 Con t 1/13/

49 Hess s Law If we multiply the first equation by 2 and reverse the second equation, they will sum together to become the third 2 S(s) + 2 O (g) 2 SO (g) ΔH = (-297 kj) (2) SO (g) + O (g) 2 SO (g) ΔH = (198 kj) (-1) S(s) + 3 O (g) 2 SO (g) ΔH = (-792 kj) 2 3 Note : ( ) + (198-1) = kj kj = kj o o o Note the change in H values with the changes in the molar coefficients to balance equation 1 and the reversal of equation 2 1/13/

50 Given the following data, Practice Problem A(s) + O 2 (g) AO 2 (g) H = 105 kj/mol A(g) + O 2 (g) AO 2 (g) H = 1200 kj/mol Find the heat required for the reaction converting: A(s) to A(g) at 298 K and 1 atm pressure. A(s) + O 2(g) AO 2(g) kj AO 2(g) A(g) + O 2(g) kj A(s) A(g) kj Note change of sign of H when 2 nd equation is reversed 1/13/

51 Standard Enthalpies of Formation The term standard state refers to the standard thermodynamic conditions chosen for substances when listing or comparing thermodynamic data: Pressure - 1 atmosphere (760 mm Hg) Temperature - (usually 25 o C). The Enthalpy change for a reaction in which reactants are in their standard states is denoted as the Standard Heat of Reaction o ΔH rxn 1/13/

52 Standard Enthalpies of Formation Standard Enthalpy of Formation of Substance The Enthalpy change for the formation of one mole of a substance in its standard state from its component elements in their standard states o ΔH f Note: The standard Enthalpy of Formation for a Pure Element (C, Fe, Au, N, etc.) in its standard state is zero 1/13/

53 Standard Enthalpies of Formation Law of Summation of Heats of Formation The Enthalpy of a reaction i.e., the Standard Heat of Reaction: ( H o rxn) is equal to the total formation energy of the products minus that of the reactants o o o rxn f f ΔH = nδh (products) - mδh (reactants) Where is the mathematical symbol meaning the sum of and m and n are the coefficients of the substances in the chemical equation, i.e., the relative number of moles of each substance 1/13/

54 Standard Enthalpies of Formation Selected Standard Heats of Formation (Enthalpies) At 25 o C (298 o K) Formula Calcium Ca(s) CaO(s) CaCO3(s) Carbon C(graphite) C(diamond) CO(g) CO 2 (g) CH 4 (g) CH 3 OH(l) HCN(g) CS 2 Chlorine Cl 2 (g) Cl(g) Cl - (aq) Cl - (g) HCl(g) Bromine Br 2 (l) Br(g) Br 2 (g) Br - (ag) Br - (g) HBr(g) H o f (kj/mol) Hydrogen H 2 (g) H(g) Oxygen O 2 (g) O 3 (g) H 2 O(g) H 2 O(l) Nitrogen N 2 (g) NH 3 (g) NO(g) Formula Sulfur S 8 (rhombic) S 8 (monoclinic) SO 2 (g) SO 3 (g) H o f (kj/mol) Formula H o f (kj/mol) 1/13/ Silver Ag(s) AgCl(s) Sodium Na(s) Na(g) NaCL(s)

55 Practice Problem Calculate the Heat of Reaction, H rxn, for the combustion of C 3 H 6 (g): C 3 H 6 (g) + 9/2 O 2 (g) 3 CO 2 (g) + 3 H 2 O(l) H o f values in kilojoules per mole are as follows: C 3 H 6 (g) = 21 CO 2 (g) = 394 H 2 O(l) = 286 a kj b kj c. 701 kj d kj e kj Ans: a o o o rxn f f o rxn o rxn o rxn ΔH = n ΔH (products) - m ΔH (reactants) ΔH = kj ΔH = ΔH = /13/

56 Practice Problem Acetylene burns in air according to the equation below. Given: H o f CO 2 (g) = kj/mol H o f H 2 O(g) = kj/mol o rxn C H (g) + 5 / 2 O (g) 2 CO (g) + H O(g) ΔH = kj Calculate H o f of C 2 H 2 (g) o o o ΔH rxn = 2 mol (Δ H f, CO 2(g)) + 1 mol (Δ H f, H2O(g)) - o o 1 mol (Δ H f, C2H 2(g)) + 5 / 2 mol (Δ H f, O 2(g)) kj = 2 mol ( kj / mol) + 1 mol ( kj / mol) - o 1 mol ( (Δ H f, C2H 2(g) + 5 / 2 mol (0.0) o f kJ = kJ kJ - 1 mol (Δ H, C H (g)) ΔH, C H (g) = o f kj -mol = kj / mol 1/13/

57 Summary Equations & Relationships E = 1 / 2 m v k 2 ΔE = E final - E initial = E products - Ereactants w = - P Δ V = - P (V - V ) ΔE = q p + w q p = ΔE + P ΔV ΔH = ΔE + P ΔV q = sm ΔT lost final initial ΔE = q p + (-P ΔV) ΔH = q p (at Constant P) -q (exothermic) = q (endothermic) gained o o o rxn f f ΔH = nδ H (products) - mδ H (reactants) 1/13/

Thermochemistry. Dr.ssa Rossana Galassi Energy Heat and work Chemical energy Internal energy PV work

Thermochemistry. Dr.ssa Rossana Galassi Energy Heat and work Chemical energy Internal energy PV work Thermochemistry Dr.ssa Rossana Galassi 320 4381420 rossana.galassi@unicam.it Energy Heat and work Chemical energy Internal energy PV work A chemical system and its surroundings. Thermodynamics is the study

More information

Chapter 6: First Law. 6.1 Forms of Energy and Their Interconversion. 6.2 Enthalpy: Heats of Reaction and Chemical Change

Chapter 6: First Law. 6.1 Forms of Energy and Their Interconversion. 6.2 Enthalpy: Heats of Reaction and Chemical Change Chapter 6 Thermochemistry: Energy Flow and Chemical Change Slide 6-1 1 Thermochemistry: Energy Flow and Chemical Change 6.1 Forms of Energy and Their Interconversion 6.2 Enthalpy: Heats of Reaction and

More information

6.1 Some basic principles

6.1 Some basic principles Ch 6 Thermochemistry: Energy Flow and Chemical Change 6.1 Forms of Energy and Their Interconversion 6.2 Enthalpy: Heats of Reaction and Chemical Change 6.3 Calorimetry: Laboratory Measurement of Heats

More information

Chapter 8 Thermochemistry: Chemical Energy. Chemical Thermodynamics

Chapter 8 Thermochemistry: Chemical Energy. Chemical Thermodynamics Chapter 8 Thermochemistry: Chemical Energy Chapter 8 1 Chemical Thermodynamics Chemical Thermodynamics is the study of the energetics of a chemical reaction. Thermodynamics deals with the absorption or

More information

Energy Changes in Chemical Reactions. System loses heat (negative); gains heat (positive) Describe the difference between the two.

Energy Changes in Chemical Reactions. System loses heat (negative); gains heat (positive) Describe the difference between the two. Energy Changes in Chemical Reactions Most reactions give off or absorb energy Energy is the capacity to do work or supply heat. Heat: transfer of thermal (kinetic) energy between two systems at different

More information

Some Simple Thermochemical Rules & Laws

Some Simple Thermochemical Rules & Laws Thermochemical Equations A chemical equation may look like the following: CH 4 + 2O 2 CO 2 + 2H 2 O A THERMOCHEMICAL equation looks like the following: CH 4 (g) + 2O 2 (g) CO 2 (g) + 2H 2 O(l), ΔH = 890kJ

More information

Section 1 Thermochemistry

Section 1 Thermochemistry Preview Objectives Thermochemistry Heat and Temperature Specific Heat Enthalpy of Reaction Enthalpy of Formation Stability and Enthalpy of Formation Enthalpy of Combustion Calculating Enthalpies of Reaction

More information

The Nature of Energy. Energy Units. The Nature of Energy. Conservation of Energy. Energy Units. Chapter 6 Energy and Chemical Reactions

The Nature of Energy. Energy Units. The Nature of Energy. Conservation of Energy. Energy Units. Chapter 6 Energy and Chemical Reactions The Nature of Energy John W. Moore Conrad L. Stanitski Peter C. Jurs http://academic.cengage.com/chemistry/moore Energy (E) = the capacity to do work. Work (w) occurs when an object moves against a resisting

More information

Section 11.1 The Flow of Energy - Heat. Chapter 11 - Thermochemistry Heat and Chemical Change. Energy and Heat. Energy and Heat

Section 11.1 The Flow of Energy - Heat. Chapter 11 - Thermochemistry Heat and Chemical Change. Energy and Heat. Energy and Heat Chapter 11 - Thermochemistry Heat and Chemical Change Adapted from notes by Stephen Cotton Section 11.1 The Flow of Energy - Heat OBJECTIVES: Explain the relationship between energy and heat. Distinguish

More information

Chapter 6: Thermochemistry (Chemical Energy) (Ch6 in Chang, Ch6 in Jespersen)

Chapter 6: Thermochemistry (Chemical Energy) (Ch6 in Chang, Ch6 in Jespersen) Chapter 6: Thermochemistry (Chemical Energy) (Ch6 in Chang, Ch6 in Jespersen) Energy is defined as the capacity to do work, or transfer heat. Work (w) - force (F) applied through a distance. Force - any

More information

Chapter 9: Energy and Chemistry

Chapter 9: Energy and Chemistry Chapter 9: Energy and Chemistry Terminology Conservation of Energy Heat Capacity and Calorimetry Enthalpy Hess s Law and Heats of Reaction Energy and Stoichiometry The rate of a reaction depends on the

More information

C H E M 1 CHEM 101-GENERAL CHEMISTRY CHAPTER 9 ENERGY & CHEMISTRY INSTR : FİLİZ ALSHANABLEH

C H E M 1 CHEM 101-GENERAL CHEMISTRY CHAPTER 9 ENERGY & CHEMISTRY INSTR : FİLİZ ALSHANABLEH C H E M 1 CHEM 101-GENERAL CHEMISTRY CHAPTER 9 ENERGY & CHEMISTRY 0 1 INSTR : FİLİZ ALSHANABLEH CHAPTER 9 ENERGY & CHEMISTRY Defining Energy Energy Transformation & Conservation of Energy Heat Capacity

More information

Thermochemistry. Thermochemistry 1/25/2010. Reading: Chapter 5 (omit 5.8) As you read ask yourself

Thermochemistry. Thermochemistry 1/25/2010. Reading: Chapter 5 (omit 5.8) As you read ask yourself Thermochemistry Reading: Chapter 5 (omit 5.8) As you read ask yourself What is meant by the terms system and surroundings? How are they related to each other? How does energy get transferred between them?

More information

Chapter 7: Thermochemistry. Contents

Chapter 7: Thermochemistry. Contents General Chemistry Principles and Modern Applications Petrucci Harwood Herring 9 th Edition Chapter 7: Thermochemistry Dr. Chris Kozak Memorial University of Newfoundland, Canada General Chemistry: Chapter

More information

CHEM 1411, chapter 6. Thermochemistry Exercises

CHEM 1411, chapter 6. Thermochemistry Exercises CHEM 1411, chapter 6. Thermochemistry Exercises 1. The heat capacity of 20.0 g of water is 83.7 J/ C. A) True B) False 2. Find the heat absorbed from the surroundings when 15 g of O 2 reacts according

More information

CHEMISTRY Practice exam #4 answer key October 16, 2007

CHEMISTRY Practice exam #4 answer key October 16, 2007 CHEMISTRY 123-01 Practice exam #4 answer key October 16, 2007 1. An endothermic reaction causes the surroundings to a. warm up. b. become acidic. c. condense. 2. Which of the following is an example of

More information

Section 1 Energy Transfer. A sample can transfer energy to another sample. One of the simplest ways energy is transferred is as heat.

Section 1 Energy Transfer. A sample can transfer energy to another sample. One of the simplest ways energy is transferred is as heat. Section 1 Energy Transfer Energy as Heat A sample can transfer energy to another sample. One of the simplest ways energy is transferred is as heat. Heat is the energy transferred between objects that are

More information

Name Date Class THERMOCHEMISTRY. SECTION 17.1 THE FLOW OF ENERGY HEAT AND WORK (pages 505 510)

Name Date Class THERMOCHEMISTRY. SECTION 17.1 THE FLOW OF ENERGY HEAT AND WORK (pages 505 510) 17 THERMOCHEMISTRY SECTION 17.1 THE FLOW OF ENERGY HEAT AND WORK (pages 505 510) This section explains the relationship between energy and heat, and distinguishes between heat capacity and specific heat.

More information

Chapter 5 Thermochemistry

Chapter 5 Thermochemistry Chapter 5 Thermochemistry I. Nature of Energy Energy units SI unit is joule, J From E = 1/2 mv 2, 1J = 1kg. m 2 /s 2 Traditionally, we use the calorie as a unit of energy. 1 cal = 4.184J (exactly) The

More information

Standard States. Standard Enthalpy of formation

Standard States. Standard Enthalpy of formation Standard States In any thermochemical equation, the states of all reactants and products must be specified; otherwise it becomes difficult for scientists to understand the experimental results of other

More information

Thermochemistry. Chapter 6. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Thermochemistry. Chapter 6. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Thermochemistry Chapter 6 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Energy is the capacity to do work Radiant energy comes from the sun and is earth s primary

More information

THERMOCHEMISTRY & DEFINITIONS

THERMOCHEMISTRY & DEFINITIONS THERMOCHEMISTRY & DEFINITIONS Thermochemistry is the study of the study of relationships between chemistry and energy. All chemical changes and many physical changes involve exchange of energy with the

More information

ENERGY. Thermochemistry. Heat. Temperature & Heat. Thermometers & Temperature. Temperature & Heat. Energy is the capacity to do work.

ENERGY. Thermochemistry. Heat. Temperature & Heat. Thermometers & Temperature. Temperature & Heat. Energy is the capacity to do work. ENERGY Thermochemistry Energy is the capacity to do work. Chapter 6 Kinetic Energy thermal, mechanical, electrical, sound Potential Energy chemical, gravitational, electrostatic Heat Heat, or thermal energy,

More information

Chapter 5 Thermochemistry

Chapter 5 Thermochemistry Chapter 5 Thermochemistry Learning Outcomes: Interconvert energy units Distinguish between the system and the surroundings in thermodynamics Calculate internal energy from heat and work and state sign

More information

Chapter 5 - Thermochemistry

Chapter 5 - Thermochemistry Chapter 5 - Thermochemistry Study of energy changes that accompany chemical rx s. I) Nature of Energy Energy / Capacity to do work Mechanical Work w = F x d Heat energy - energy used to cause the temperature

More information

Thermochemistry: study of the relationships between chemistry and energy. Energy: capacity to do work

Thermochemistry: study of the relationships between chemistry and energy. Energy: capacity to do work Chapter 6: Thermochemistry Thermochemistry: study of the relationships between chemistry and energy Energy: capacity to do work Work:result of a force acting over a certain distance, one way to transfer

More information

Chapter 6: Energy Relationships in Chemical Reactions. Energy Relationships in Chemical Reactions

Chapter 6: Energy Relationships in Chemical Reactions. Energy Relationships in Chemical Reactions Energy Relationships in Chemical Reactions Chapter 6 Chapter 6: Energy Relationships in Chemical Reactions I. Energy, work, heat II. Internal Energy, E Energy transfer ΙΙΙ. ΔH (q p ) vs ΔE (q v ) IV. Thermochemical

More information

Chapter Six. Energy Relationships in Chemical Reactions

Chapter Six. Energy Relationships in Chemical Reactions Chapter Six Energy Relationships in Chemical Reactions 1 Energy (U): Capacity to Do Work Radiant energy Energy from the sun Nuclear energy Energy stored in the nucleus of an atom Thermal energy Energy

More information

THERMOCHEMISTRY. [MH5; Chapter 8]

THERMOCHEMISTRY. [MH5; Chapter 8] THERMOCHEMISTRY [MH5; Chapter 8] Thermochemistry is the study of the heat flow that accompanies chemical reactions. PRINCIPLES OF HEAT FLOW [MH5; 8.1] Heat is a process whereby energy is transferred from

More information

Energy & Chemical Change

Energy & Chemical Change & Chemical Change CHAPTER 7 Chemistry: The Molecular Nature of Matter, 6 th edition By Jesperson, Brady, & Hyslop 1 CHAPTER 7: & Chemical Change Learning Objectives! Potential vs Kinetic! Internal, Work,

More information

Did you miss an exam? Download a Makeup Request Form from Angel > Exam Schedule

Did you miss an exam? Download a Makeup Request Form from Angel > Exam Schedule Week 13: Lectures 37 39 Lecture 37: W 11/16 Lecture 38: F 11/18 Lecture 39: M 11/28 Reading: BLB Ch 4.6; 10.5; 8.8; 5.3 5.7 Homework: BLB 10: 57; 5: 4, 17, 29, 37, 39, 53, 55, 83, 85; 8: 65a, 67ac, 72ab,

More information

d. conditions required to attain equilibrium. (not in this chapter) e. forces driving processes that occur spontaneously. (not in this chapter)

d. conditions required to attain equilibrium. (not in this chapter) e. forces driving processes that occur spontaneously. (not in this chapter) CHAPTER SIX: THERMOCHEMISTRY 1. Thermochemistry is a branch of chemistry concerned with energy changes accompanying chemical and physical processes. 2. Examples: a. heat liberated in a chemical reaction.

More information

3. Of energy, work, enthalpy, and heat, how many are state functions? a) 0 b) 1 c) 2 d) 3 e) 4 ANS: c) 2 PAGE: 6.1, 6.2

3. Of energy, work, enthalpy, and heat, how many are state functions? a) 0 b) 1 c) 2 d) 3 e) 4 ANS: c) 2 PAGE: 6.1, 6.2 1. A gas absorbs 0.0 J of heat and then performs 15.2 J of work. The change in internal energy of the gas is a) 24.8 J b) 14.8 J c) 55.2 J d) 15.2 J ANS: d) 15.2 J PAGE: 6.1 2. Calculate the work for the

More information

Chapter 5 Thermochemistry

Chapter 5 Thermochemistry Chapter 5 Thermochemistry Transferring Energy Energy is the ability to do work or transfer heat. Energy used to cause an object that has mass to move is called work. (W = F x d) Energy used to cause the

More information

Thermochemistry. Chapter 17

Thermochemistry. Chapter 17 Thermochemistry Chapter 17 Thermochemistry The study of energy changes that occur during chemical reactions and changes in state. The amount of heat gained/lost by the system must equal that gained/lost

More information

Chapter 6. Quantities in Chemical Reactions. Introduction. Chapter 6 Topics. Internal Combustion Engine. Amounts of Reactants and Products

Chapter 6. Quantities in Chemical Reactions. Introduction. Chapter 6 Topics. Internal Combustion Engine. Amounts of Reactants and Products Chapter 6 Quantities in Chemical Reactions Introduction How can we predict amounts of reactants and products in a reaction, such as that in an internal combustion engine? How can we predict the amount

More information

Thermochem: It s DYNAMIC!

Thermochem: It s DYNAMIC! Thermochem: It s DYNAMIC! Presented by: Hiral Mathur Pre-AP, AP, and Advanced Placement are registered trademarks of the College Board, which was not involved in the production of, and does not endorse,

More information

Name: Thermochemistry. Practice Test B. General Chemistry Honors Chemistry

Name: Thermochemistry. Practice Test B. General Chemistry Honors Chemistry Name: Thermochemistry B Practice Test B General Chemistry Honors Chemistry 1 Objective 1: Use the relationship between mass, specific heat, and temperature change to calculate the heat flow during a chemical

More information

Thermochemistry. Energy Flow in Thermochemistry

Thermochemistry. Energy Flow in Thermochemistry Thermochemistry! part of thermodynamics (study of heat)! the study of energy transfer during reactions! defined through system and surroundings Energy Flow in Thermochemistry!E = E final - E initial =

More information

The Relationships Between. Internal Energy, Heat, Enthalpy, and Calorimetry

The Relationships Between. Internal Energy, Heat, Enthalpy, and Calorimetry The Relationships Between Internal Energy, Heat, Enthalpy, and Calorimetry Recap of Last Class Last class, we began our discussion about energy changes that accompany chemical reactions Chapter 5 discusses:

More information

Chapter 6. Homework. Thermodynamics vs. Kinetics. Energy. Energy Unit. Chapter 6. Principles of Reactivity: Energy and Chemical Reactions

Chapter 6. Homework. Thermodynamics vs. Kinetics. Energy. Energy Unit. Chapter 6. Principles of Reactivity: Energy and Chemical Reactions Homework Chapter 6 Chapter 6 29, 33, 35, 39, 45, 49, 53, 57, 63, 67, 71, 79, 87 Principles o Reactivity: and Chemical Reactions Thermodynamics vs. Kinetics A.E. Kinetics E or H Reaction Coordinate What

More information

Chapter 6. Thermochemistry

Chapter 6. Thermochemistry Chapter 6 Thermochemistry Pressure Volume Work PV work is work caused by a volume change against an external pressure. When gases expand, ΔV is +, but the system is doing work on the surroundings, so wgas

More information

Thermochemistry Test Preview

Thermochemistry Test Preview Thermochemistry Test Preview Matching Match each item with the correct statement below. a. calorimeter d. enthalpy b. calorie e. specific heat c. joule f. heat capacity 1. quantity of heat needed to raise

More information

17.1 The Flow of Energy Heat and Work

17.1 The Flow of Energy Heat and Work Presentations Chapter 17 Topic Thermochemistry Name Date Hour Principles of Chemistry 17.1 The Flow of Energy Heat and Work 1. In what direction does heat flow? How is heat represented? Why does heat flow?

More information

245J specific heat = J / g K 14.4g 38.0K. 3. What quantity of energy is required to heat 50.0 g of water from 25.0 o C to 95 o C?

245J specific heat = J / g K 14.4g 38.0K. 3. What quantity of energy is required to heat 50.0 g of water from 25.0 o C to 95 o C? Chem 112-2014 Name: ANSWER KEY Vining- Exam #1 February 7, 2014 1. Specific heat capacity is a) the quantity of heat needed to change the temperature of 1.00 g of a substance by 1.00 K. Note: This is the

More information

Chapter 5. Thermochemistry

Chapter 5. Thermochemistry Chapter 5. Thermochemistry THERMODYNAMICS - study of energy and its transformations Thermochemistry - study of energy changes associated with chemical reactions Energy - capacity to do work or to transfer

More information

Practice Test Questions:

Practice Test Questions: Practice Test Questions: There are a lot of questions. Please feel free to do a problem, skip around and make sure you are doing all types of problems heat exchange, Hess Law problems, specific heat problems,

More information

Thermochemistry. Chapter 6. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Thermochemistry. Chapter 6. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Thermochemistry Chapter 6 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Energy is the capacity to do work. Radiant energy comes from the sun and is earth s

More information

H 2 (g) + ½ O 2 (g) H 2 O(l) H o f [NO(g)] = 90.2 kj/mol; H o f [H 2 O(g)] = kj/mol H o f [NH 3 (g)] = kj/mol; H o f [O 2 (g)] =?

H 2 (g) + ½ O 2 (g) H 2 O(l) H o f [NO(g)] = 90.2 kj/mol; H o f [H 2 O(g)] = kj/mol H o f [NH 3 (g)] = kj/mol; H o f [O 2 (g)] =? Chapter 16 Thermodynamics GCC CHM152 Thermodynamics You are responsible for Thermo concepts from CHM 151. You may want to review Chapter 8, specifically sections 2, 5, 6, 7, 9, and 10 (except work ). Thermodynamics:

More information

Chapter 5 Thermochemistry

Chapter 5 Thermochemistry Chapter 5 Thermochemistry Thermochemistry Open Closed Isolated Nov. 2006 Exchange: Mass & energy Energy Nothing Energy Changes in Chemical Reactions Exothermic process : any process that gives off heat

More information

Example: orange juice from frozen concentrate.

Example: orange juice from frozen concentrate. Dilution: a process in which the concentration (molarity) of a solution is lowered. The amount of solute (atoms, moles, grams, etc.) remains the same, but the volume is increased by adding more solvent.

More information

Lecture 38: Thermochemistry 1

Lecture 38: Thermochemistry 1 Lecture 38: Thermochemistry 1 Read: BLB 5.3 5.5 HW: BLB 5:4,6,17,29,37,39,41,53,55 Know: REVIEW Lectures 2 & 26 energy enthalpy enthalpy of reactions calorimetry Check out the grad-u-lator on the Chem110

More information

AP* Chemistry THERMOCHEMISTRY

AP* Chemistry THERMOCHEMISTRY AP* Chemistry THERMOCHEMISTRY Terms for you to learn that will make this unit understandable: Energy (E) the ability to do work or produce heat ; the sum of all potential and kinetic energy in a system

More information

Energy and States of Matter

Energy and States of Matter Chapters 3, 7 and 10 Energy and States of Matter Potential and Kinetic Energy Potential energy, PE, is stored energy; it results from position or composition. Kinetic energy, KE, is the energy matter has

More information

Motivation. Chemistry 431. Enthalpy for reactions involving gases. Molar Enthalpy. The temperature dependence of the enthalpy change

Motivation. Chemistry 431. Enthalpy for reactions involving gases. Molar Enthalpy. The temperature dependence of the enthalpy change Chemistry 431 Lecture 7 Enthalpy Motivation The enthalpy change ΔH is the change in energy at constant pressure. When a change takes place in a system that is open to the atmosphere, the volume of the

More information

Chapter 5 Thermo. Energy & Chemistry. Energy & Chemistry. Units of Energy. Energy & Chemistry. Potential & Kinetic Energy. Some Basic Principles

Chapter 5 Thermo. Energy & Chemistry. Energy & Chemistry. Units of Energy. Energy & Chemistry. Potential & Kinetic Energy. Some Basic Principles 1 Energy & Chemistry effrey Mack California State University, Sacramento Chapter 5 Principles of Chemical Reactivity: Energy and Chemical Reactions Questions that need to be addressed: How do we measure

More information

CHM 101 THERMOCHEMISTRY

CHM 101 THERMOCHEMISTRY CHM 101 THERMOCHEMISTRY DEFINITIONS ENERGY is the capacity to do work Kinetic energy E k = 0.5 mv 2 (i) Potential energy is energy an object possess by virtue of its position PE = mgh (ii) Where h is the

More information

Chapter 5: Thermochemistry

Chapter 5: Thermochemistry Chapter 5 Thermochemistry 5-1 Chapter 5: Thermochemistry Chapter 5 5.1 Energy 5.2 Enthalpy 5.3 Energy, Temperature Changes, and Changes of State 5.4 Enthalpy Changes and Chemical Reactions 5.5 Hess s Law

More information

Thermochemistry Example Problems

Thermochemistry Example Problems Recognizing Endothermic & Exothermic Processes Thermochemistry Example Problems On a sunny winter day, the snow on a rooftop begins to melt. As the melted water drips from the roof, it refreezes into icicles.

More information

Chapter 7 Chemical Reactions and Energy Flow

Chapter 7 Chemical Reactions and Energy Flow Chapter 7 Chemical Reactions and Energy Flow Energy is the currency of the Universe. Chemical changes are usually accompanied by a redistribution of energy and not just matter. And whether or not a reaction

More information

Work Increases Pressure Recall Gas Laws: P V = k T

Work Increases Pressure Recall Gas Laws: P V = k T Unit 1B Thermodynamics Thermodynamics is the study of the effects of work, heat, and energy on a system What s the relation between Work, Heat, & Energy? Work Increases Pressure Recall Gas Laws: P V =

More information

Name: Thermochemistry. Practice Test A. General Chemistry Honors Chemistry

Name: Thermochemistry. Practice Test A. General Chemistry Honors Chemistry Name: Thermochemistry Practice Test A General Chemistry Honors Chemistry 1 Objective 1: Use the relationship between mass, specific heat, and temperature change to calculate the heat flow during a chemical

More information

STOICHIOMETRY. - the study of the quantitative aspects of chemical

STOICHIOMETRY. - the study of the quantitative aspects of chemical STOICHIOMETRY - the study of the quantitative aspects of chemical GENERAL PLAN FOR STOICHIOMETRY Mass reactant Mass product Moles reactant Stoichiometric factor Moles product STOICHIOMETRY It rests on

More information

Chapter 19 thermodynamics Laws of thermodynamics:

Chapter 19 thermodynamics Laws of thermodynamics: Chapter 19 thermodynamics Laws of thermodynamics: Outline major components of the Chapter, focus of topics we covered over and over again, surprise #5, lab, demos, videos, etc. 0 th Law of Thermodynamics

More information

Chapter 5 Thermochemistry

Chapter 5 Thermochemistry Chapter 5 Thermochemistry Every chemical and physical process involves an exchange of energy between the reaction and the rest of the universe. Thermochemistry involves the study of this exchange of energy.

More information

Name Class Date. The enthalpy of the final reaction can be rewritten using the following equation. H reaction sum of H 0 f products

Name Class Date. The enthalpy of the final reaction can be rewritten using the following equation. H reaction sum of H 0 f products Skills Worksheet Problem Solving Thermochemistry Thermochemistry deals with the changes in energy that accompany a chemical reaction. Energy is measured in a quantity called enthalpy, represented as H.

More information

4. The total energy of the universe is constant. Energy cannot be created or destroyed, but can only be converted from one form to another.

4. The total energy of the universe is constant. Energy cannot be created or destroyed, but can only be converted from one form to another. CHAPTER 10 1. energy 2. Potential energy is energy due to position or composition. A stone at the top of a hill possesses potential energy since the stone may eventually roll down the hill. A gallon of

More information

Bomb Calorimetry. Example 4. Energy and Enthalpy

Bomb Calorimetry. Example 4. Energy and Enthalpy Bomb Calorimetry constant volume often used for combustion reactions heat released by reaction is absorbed by calorimeter contents need heat capacity of calorimeter q cal = q rxn = q bomb + q water Example

More information

Chemistry Thermochemistry Lesson 10 Lesson Plan David V. Fansler

Chemistry Thermochemistry Lesson 10 Lesson Plan David V. Fansler Chemistry Thermochemistry Lesson 10 Lesson Plan David V. Fansler The Flow of Energy-Heat Objectives: Explain the relationship between energy and heat; Distinguish between heat capacity and specific heat.

More information

Chemistry 1A. Chapter 6

Chemistry 1A. Chapter 6 Chemistry 1A Chapter 6 Some Chemical Changes Release Energy Combustion of Methane CH 4 (g) + 2O 2 (g) CO 2 (g) + 2H 2 O(l) + Some Chemical Changes Absorb Energy Energy Terms Energy = the capacity to do

More information

General Chemistry I

General Chemistry I Thermochemistry General Chemistry I 2302101 Dr Rick Attrill Oice MHMK 1405/5 The Nature o Energy and Types o Energy Energy Changes in Chemical Reactions Introduction to Thermodynamics Enthalpy o Chemical

More information

Forms of Energy and Their Interconversion. all energy is either poten:al or kine:c energy

Forms of Energy and Their Interconversion. all energy is either poten:al or kine:c energy Chapter 6. Thermochemistry Drawing by Karen Thurber To create a rabbit, the magician must summon up the energy of the rabbit as well as some additional energy, equal to PV, to push the atmosphere out of

More information

Chemical Reactions. PE Diagrams Thermochemical Equations Hess s Law Bond Energy. STSE: What Fuels You?

Chemical Reactions. PE Diagrams Thermochemical Equations Hess s Law Bond Energy. STSE: What Fuels You? Unit Outline Temperature and Kinetic Energy Heat/Enthalpy Calculation Temperature changes (q = mcδt) Phase changes (q = nδh) Heating and Cooling Curves Calorimetry (q = CΔT & above formulas) Chemical Reactions

More information

CHAPTER 5 & 6 PRACTICE TEST QUESTIONS

CHAPTER 5 & 6 PRACTICE TEST QUESTIONS CHAPTER 5 & 6 PRACTICE TEST QUESTIONS Information that most likely will be on the front cover of your exam: R = 0.0821 Latm/molK Rate a f = Rate b w molar mass s b f molar mass a 1 atm = 760 mm Hg = 760

More information

Bond Enthalpy. Energy is released when bonds are formed (exothermic) Energy must be supplied when bonds are broken (endothermic)

Bond Enthalpy. Energy is released when bonds are formed (exothermic) Energy must be supplied when bonds are broken (endothermic) Bond Enthalpy Bond Enthalpy ( H Dissociation ) is the enthalpy change in a reaction in which a chemical bond is broken in the gas phase. Bond Energy is the energy needed to break 1 mol of the particular

More information

EXPERIMENT 9. Thermochemistry: Hess Law and the Heat of Formation of MgO

EXPERIMENT 9. Thermochemistry: Hess Law and the Heat of Formation of MgO Outcomes EXPERIMENT 9 Thermochemistry: Hess Law and the Heat of Formation of MgO After completing this experiment, the student should be able to: 1. Differentiate between exothermic and endothermic reactions.

More information

Thermochemistry the study of changes that occur during chemical reactions and changes in state.

Thermochemistry the study of changes that occur during chemical reactions and changes in state. Chemistry Chapter 17 Notes FIVE-STEP DIAGRAM Name Date Block Temperature Change Equation ΔH (q)= m = Cp = ΔT = Phase Change Equation ΔH = mol = ΔHphase change = THERMOCHEMISTRY INTRO Thermochemistry the

More information

Thermochemistry. Potential Energy is stored energy E P = mgh where m = mass, g = constant acceleration of gravity and h = height

Thermochemistry. Potential Energy is stored energy E P = mgh where m = mass, g = constant acceleration of gravity and h = height Thermochemistry Thermochemistry is the science of relationships between heat and energy, which is one area of thermodynamics - the study of energy and its transformations. Energy is the potential or capacity

More information

Thermochemical equations allow stoichiometric calculations.

Thermochemical equations allow stoichiometric calculations. CHEM 1105 THERMOCHEMISTRY 1. Change in Enthalpy ( H) Heat is evolved or absorbed in all chemical reactions. Exothermic reaction: heat evolved - heat flows from reaction mixture to surroundings; products

More information

Chemical reactions involve a transfer of energy between the system and the surroundings.

Chemical reactions involve a transfer of energy between the system and the surroundings. THERMODYNAMICS science of the interconversion of different forms of ENERGY e.g. heat and work an essential foundation for understanding physical sciences. at the centre of any physical description Key

More information

Temperature and Heat

Temperature and Heat Temperature and Heat Energy: capacity to do work Kinetic energy (associated with motion) Thermal, atoms, molecules, and ions are in motion all matter has thermal energy Mechanical, moving tennis ball,

More information

State Functions -depend only on the current state of the system.

State Functions -depend only on the current state of the system. #47 Notes Ch. 6 Thermochemistry (Thermodynamics) -is the study of energy. I. Energy is the capacity to do work or produce heat. Law of Conservation of Energy Energy cannot be created or destroyed, just

More information

PHASE AND CHEMICAL CHANGES. a change in the state of matter without any change in the chemical composition of the system.

PHASE AND CHEMICAL CHANGES. a change in the state of matter without any change in the chemical composition of the system. Phase Change PHASE AND CHEMICAL CHANGES 1 a change in the state of matter without any change in the chemical composition of the system. These changes can be either: exothermic - energy is released from

More information

Thermochemistry. Chapter 6. Concept Check 6.1. Concept Check 6.2. Solution

Thermochemistry. Chapter 6. Concept Check 6.1. Concept Check 6.2. Solution Chapter 6 Thermochemistry Concept Check 6.1 A solar-powered water pump has photovoltaic cells on protruding top panels. These cells collect energy from sunlight, storing it momentarily in a battery, which

More information

= J K. 1. Which sample contains the fewest atoms? a. 10 g of C b. 10 g of Ne c. 10 g of H d. 10 g of O. ANSWER: b

= J K. 1. Which sample contains the fewest atoms? a. 10 g of C b. 10 g of Ne c. 10 g of H d. 10 g of O. ANSWER: b CHEM 101 Fall 07 Final Exam On the answer sheet (scantron) write your Name, Student ID Number, and Recitation Section Number. Choose the best (most correct) answer for each question AND ENTER IT ON YOUR

More information

CHAPTER 6 THERMOCHEMISTRY: ENERGY FLOW AND CHEMICAL CHANGE

CHAPTER 6 THERMOCHEMISTRY: ENERGY FLOW AND CHEMICAL CHANGE CHAPTER 6 THERMOCHEMISTRY: ENERGY FLOW AND CHEMICAL CHANGE CHEMICAL CONNECTIONS BOXED READING PROBLEMS B6.1 Plan: Convert the given mass in kg to g, divide by the molar mass to obtain moles, and convert

More information

HEAT, TEMPERATURE, & THERMAL ENERGY

HEAT, TEMPERATURE, & THERMAL ENERGY HEAT, TEMPERATURE, & THERMAL ENERGY Energy A property of matter describing the ability to do. Work - is done when an object is moved through a distance by a force acting on the object. Kinetic Energy Associated

More information

Energy and Chemical Change

Energy and Chemical Change Energy and Chemical Change Section 15.1 Section 15.2 Section 15.3 Section 15.4 Section 15.5 Energy Heat Thermochemical Equations Calculating Enthalpy Change Reaction Spontaneity Click a hyperlink or folder

More information

Stoichiometry of Thermochemical Equations

Stoichiometry of Thermochemical Equations Stoichiometry of Thermochemical Equations A thermochemical reaction is a balanced equation that includes the heat of reaction, H rxn The amounts (moles) of substance and their states of matter are shown

More information

Purpose The purpose of this activity is to determine the amount of energy produced or consumed during several chemical reactions.

Purpose The purpose of this activity is to determine the amount of energy produced or consumed during several chemical reactions. Chemistry Name: Date: KEY 330.06.04.1a Energy: Enthalpy of Thermochemical Reactions 1 Purpose The purpose of this activity is to determine the amount of energy produced or consumed during several chemical

More information

Thermodynamics. Thermodynamics: the physics of heat movement. Thermochemistry: the thermodynamics of chemical reactions.

Thermodynamics. Thermodynamics: the physics of heat movement. Thermochemistry: the thermodynamics of chemical reactions. Thermodynamics Thermodynamics: the physics of heat movement. Thermochemistry: the thermodynamics of chemical reactions. In most physical and chemical processes there is an energy change energy is transferred

More information

Chapter 5 Thermochemistry: Energy Changes in Reactions

Chapter 5 Thermochemistry: Energy Changes in Reactions Chapter 5 Thermochemistry: Energy Changes in Reactions Chapter Objectives: Understand potential and kinetic energy, and the first law of thermodynamics. Understand the concept of enthalpy, and use standard

More information

1/7/2013. Chapter 10. Energy Changes in Chemical Reactions. Chemistry: Atoms First Julia Burdge & Jason Overby. Thermochemistry

1/7/2013. Chapter 10. Energy Changes in Chemical Reactions. Chemistry: Atoms First Julia Burdge & Jason Overby. Thermochemistry /7/03 Chemistry: Atoms First Julia Burdge & Jason Overby 0 Thermochemistry Chapter 0 Energy Changes in Chemical Reactions Kent L. McCorkle Cosumnes River College Sacramento, CA Copyright (c) The McGraw-Hill

More information

Chapter 6 Quantities in Chemical Reactions

Chapter 6 Quantities in Chemical Reactions Chapter 6 Quantities in Chemical Reactions The Meaning of a Balanced Chemical Equation Mole-Mole Conversions Mass-Mass Conversions Limiting Reactants Percent Yield Energy Changes Copyright The McGraw-Hill

More information

Thermochemistry. 1. Stoichiometry # g ΔHrxn where n = moles in the reaction for the specific substance Mm n

Thermochemistry. 1. Stoichiometry # g ΔHrxn where n = moles in the reaction for the specific substance Mm n Thermochemistry Review 1. Stoichiometry # g ΔHrxn where n = moles in the reaction for the specific substance Mm n Exothermic Reaction (enthalpy is a product): Endothermic Reaction (enthalpy is a reactant):

More information

Example. c. Calculate the amount of heat (in kj) required to heat 1.00 kg (~1 L) of water at 25 C to its boiling point.

Example. c. Calculate the amount of heat (in kj) required to heat 1.00 kg (~1 L) of water at 25 C to its boiling point. Example When consuming an ice-cold drink, one must raise the temperature of the beverage to 37.0 C (normal body temperature). Can one lose weight by drinking ice-cold beverages if the body uses up about

More information

Sample Exercise 5.1 Describing and Calculating Energy Changes

Sample Exercise 5.1 Describing and Calculating Energy Changes Sample Exercise 5.1 Describing and Calculating Energy Changes A bowler lifts a 5.4-kg (12-lb) bowling ball from ground level to a height of 1.6 m (5.2 ft) and then drops it. (a) What happens to the potential

More information

(The heat is equal to the product of specific heat capacity, temperature rise, and mass.)

(The heat is equal to the product of specific heat capacity, temperature rise, and mass.) Assignment 05 A 1- Calculate the kinetic energy of a 7.3-kg steel ball traveling at 18.0 m/s. a) 66 J b) 4.8 x 10 3 J c) 1.2 x 10 3 J d) 2.4 x 10 3 J (The kinetic energy is equal to one-half the product

More information

Page 1. N A = x mol -1 R = mmhg = 1 h = x J s c = 3.00 x 10 8 m/s L atm

Page 1. N A = x mol -1 R = mmhg = 1 h = x J s c = 3.00 x 10 8 m/s L atm Page 1 Practice for Exam 3. Note: Many if not most of the questions below appeared on a past exam, but not necessarily on the same exam. I've also combined problems from at least two past exams onto this

More information