# ΔU = q + w = q - P ΔV. 3. What are extensive and intensive properties and some examples of each?

Save this PDF as:

Size: px
Start display at page:

Download "ΔU = q + w = q - P ΔV. 3. What are extensive and intensive properties and some examples of each?"

## Transcription

1 Worksheet 2 1. Energy and Enthalpy. A system can exchange energy with its surroundings either by transferring heat or by doing work. Using q to represent transferred heat and w = - P ΔV, the total energy change of a system, ΔU, can be represented as ΔU = q + w = q - P ΔV where q has a positive sign if the system gains heat and a negative sign if the system loses it. Rearrange this equation to give the amount of heat transferred. Then, think of two ways in which a chemical reaction might be carried out: a reaction might be carried out in a closed container with a constant volume, or carried out in an open flask that keeps the pressure constant and allows the volume of the system to change freely. Write out the two equations that would describe these two scenarios in terms of heat transfer and/or PV work. Lastly, the enthalpy (H) of a system is described by the quantity U + PV. What is the equation that relates heat to enthalpy at constant pressure? q = ΔU + P ΔV q v = ΔU At constant volume; ΔV = 0 q p = ΔU + P ΔV At constant pressure q p = ΔU + P ΔV = ΔH 2. Fill in the blanks. When reactions are performed in an open container, such as a coffee-cup calorimeter, the pressure (= atmospheric pressure) does not change and q p = ΔH; in a closed container, such as a bomb calorimeter, the volume (= volume of the bomb) does not change and q v = ΔU. Remember that even in an open container, unless a gas is involved in the reaction, volume changes are usually negligible and ΔH ΔU. 3. What are extensive and intensive properties and some examples of each? Intensive properties are values that do not depend on the sample size, such as temperature and melting point. Thus, a small ice cube might have the same temperature as a massive iceberg. Extensive properties, like length and volume, have values that do depend on the sample size. An ice cube is much smaller than an iceberg. 4. Suppose the enthalpy change when carbon monoxide is burned with oxygen to carbon dioxide is given by the reaction C(s,gr) + ½ O 2 (g) CO(g) ΔH = kj at 25 C. What is the internal energy of this reaction? ΔU = ΔH PΔV

2 ΔU = ΔH Δn g RT = kj (½ mol)(8.315 J K -1 mol -1 )(298 K) = kj 5. Calculate ΔH f (in kilojoules per mole) for benzene, C 6 H 6, from the following data: 2 C 6 H 6 (l) + 15 O 2 (g) 12 CO 2 (g) + 6 H 2 O(l) ΔH = kj ΔH f (CO 2 ) = kj/mol ΔH f (H 2 O) = kj/mol ΔH rxn = [12 ΔH f (CO 2 ) + 6 ΔH f (H 2 O)] [2 ΔH f (C 6 H 6 )] kj = [(12 mol)( kj/mol) + (6 mol)( kj/mol)] [(2 mol)( ΔH f (C 6 H 6 ))] Solve for ΔH f (C 6 H 6 ) kj = kj [(2 mol)( ΔH f (C 6 H 6 ))] 97.2 kj = (2 mol)( ΔH f (C 6 H 6 )) ΔH f (C 6 H 6 ) = kj/mol 6. Use the bond dissociation energies found in the ebook under Data and Tables to calculate an approximate ΔH (in kilojoules) for the reaction of ethylene with hydrogen to yield ethane. H 2 C=CH 2 (g) + H 2 (g) CH 3 CH 3 (g) ΔH rxn = D(Reactant bonds) D(Product bonds) ΔH rxn = (D C=C + 4 D C-H + D H-H ) (6 D C-H + D C-C ) ΔH rxn = [(1 mol)(602 kj/mol) + (4 mol)(413kj/mol) + (1 mol)(436 kj/mol)] [(6 mol)(413 kj/mol) + (1 mol)(346 kj/mol)] = -134 kj 7. In your own words describe what entropy, spontaneity, microstates are in relation to thermodynamics. Among the many ways entropy can be defined one way to describe it is the amount of molecular randomness in a system. Entropy is a thermodynamic state function of a system, determined by the number of microstates available to the molecules of the system; changes in entropy, and therefore in the number of available microstates, determine the direction of spontaneous processes. A spontaneous process is one that occurs by itself, given enough time and without any continuous external influence. Microstates are a microscopic state of a system, characterized by a particular distribution of molecules among the positions and momenta accessible to them. In other words, a microstate specifies all molecular details about the system including the position and velocity of every molecule. The more such states available to the system, among which energy can be shared, with appreciable probability, the greater the entropy. 8. Predict whether ΔS is likely to be positive or negative for each of the following reactions:

3 (a) H 2 C=CH 2 (g) + Br 2 (g) CH 2 BrCH 2 Br(l) (b) 2 C 2 H 6 (g) + 7 O 2 (g) 4 CO 2 (g) + 6 H 2 O(g) Look at each reaction and try to decide whether molecular randomness increases or decreases. Reactions that increase the number of gaseous molecules generally have a positive ΔS, while reactions that decrease the number of gaseous molecules have a negative ΔS. For (a) the amount of molecular randomness in the system decreases when 2 mol of gaseous reactants combine to give 1 mol of liquid product, so the reaction has a negative ΔS. In (b) the amount of molecular randomness in the system increases when 9 mol of gaseous reactants give 10 mol of gaseous products, so the reaction has a positive ΔS. 9. What is the equation for Gibbs free-energy change (ΔG) and what does each quantity define? Remember that the value of the free-energy change ΔG is a general criterion for the spontaneity of a chemical or physical process. Gibbs free-energy change (ΔG), ΔG = ΔH - T ΔS, determines in a chemical reaction or other process is spontaneous. ΔG stands for free-energy change, while ΔH, enthalpy, is the heat of the reaction. T stands temperature and is measured in Kelvins. Lastly ΔS is the entropy change. 10. The two gases BF 3 (g) and BCl 3 (g) are mixed in equal molar amounts. All B F bonds have about the same bond enthalpy, as do all B Cl bonds. Explain why the mixture tends to react to form BF 2 Cl(g) and BCl 2 F(g). A system containing the chemically mixed B halides has greater entropy than a system of BCl 3 and BF 3. It has the same number of gas phase molecules, but more distinguishable kinds of molecules, hence more microstates and higher entropy. 11. Tetraphenylgermane, (C 6 H 5 ) 4 Ge, has a melting point of C, and its enthalpy increases by J g -1 during fusion. Calculate the molar enthalpy of fusion and molar entropy of fusion of tetraphenylgermane. m p = C = K ΔH = J / g MW(C 6 H 5 ) 4 Ge = g / mol molar ΔH = J / g g / mol = J / mol molar ΔS = ΔH / T = J / mol K = J K -1 mol Suppose 1.00 mol of water at 25 C is flash-evaporated by allowing it to fall into an iron crucible maintained at 150 C. Calculate ΔS tot, if c p (H 2 O(l)) = 75.4 J K -1 mol -1 and c p (H 2 O(g)) = 36.0 J K -1 mol -1. Take ΔH vap = kj mol -1 for water at its boiling point of 100 C. H 2 O(l) H 2 O(l) H 2 O(g) H 2 O(g)

4 25 C 100 C 100 C 150 C q 1 = ΔH = m CΔT q 2 = ΔH = kj mol -1 q 3 = ΔH = m CΔT m = 1.00 mol H 2 O T i = 25 C = 298 K T f = 150 C = 423 K c p (H 2 O(l)) = 75.4 J K -1 mol -1 c p (H 2 O(g)) = 36.0 J K -1 mol -1 ΔH vap = kj mol -1 for H 2 O at T = 100 C. ΔH = q = (1.00 mol)(75.4 J K -1 mol -1 )(100 25) + (40680 J K -1 mol -1 )(1.00 mol) + (1.00 mol)(36.0 J K -1 mol -1 )( ) = J ΔS H2O = n c p (H 2 O(l)) ln T 2 / T 1 + n ΔH vap /T + n c p (H 2 O(g) ln T 2 / T 1 = (1.00 mol)(75.4 J K -1 mol -1 )(ln 373 K/298 K) + (1.00 mol)(40680 J mol -1 / 373 K) + (1.00 mol)(36.0 J mol -1 )(ln 423 K / 373 K) = J K -1 ΔS iron = q/t = J 423 K = J K -1 ΔS total = ΔS H2O + ΔS iron = J K J K -1 = 16.7 J K Iron has a heat capacity of 25.1 J K -1 mol -1, approximately independent of temperature between 0 and 100 C. Calculate the enthalpy and entropy change of 1.00 mol of iron as it is cooled at atmospheric pressure from 100 C to 0 C. C = 25.1 J K -1 mol -1 m = 1.00 mol T i = 100 C = 373 K T f = 0 C = 273 K ΔH = m C ΔT = (1.00 mol)(25.1 J K -1 mol -1 )(-100 K) = J ΔS = n C ln T f / T i = (1.00 mol)(25.1 J K -1 mol -1 )(ln 273 K / 373 K) = 7.83 J K A water bath is filled with lots of ice and water to maintain a constant temperature of 0 C. You dump a 10 g block of 200 C aluminum into the bath. The heat capacity of aluminum is J K -1 mol -1 and the enthalpy of fusion of water is 6 kj mol -1. (a) How much heat is transferred from the block to the water bath? n = 10 g 1mol / 27 g = 0.37 mol Al ΔH Al = q = n C ΔT = (0.37 mol)(25.35 J K -1 mol -1 )(-200 K) = J (b) How many grams of ice melt? q Al = -q H2O = n ΔH fus J = n(6000 J mol -1 ) n= 0.30 mol 18 g / 1mol = 5.4 g H 2 O (c) What is the entropy change of the aluminum block? ΔS Al = n C ln T f /T i = (0.37 mol)(24.37 J K -1 mol -1 )(ln 273 K / 473 K) = J K -1

5 (d) What is the entropy change of the water bath? ΔS H2O = ΔH H2O / T = J/ 273K = 6.6 J K -1 (e) What is the total entropy change? ΔS tot = ΔS Al + ΔS H2O = J K J K -1 = 1.65 J K The following reaction is performed at a constant temperature of 298 K and a pressure of 1 atm. Given that ΔH f (NH 3 )(g) = kj mol -1 and ΔG f (NH 3 )(g) = kj mol -1. N 2 (g) + 3H 2 (g) 2NH 3 (g) If the reaction moves from reactants to products what sign would you expect for each of the following: q Positive Negative Zero No Way to Know w Positive Negative Zero No Way to Know ΔH (system) Positive Negative Zero No Way to Know ΔS (system) Positive Negative Zero No Way to Know Comparing the energy and the enthalpy you would expect which of the following describes this reaction: ΔH > ΔU ΔH < ΔU ΔH = ΔU Do you expect the reaction to be spontaneous? Yes No If Yes or No is there a temperature at which it will be nonspontaneous/spontaneous? Yes ΔG = ΔH - T ΔS ΔS = (ΔG ΔH) / -T = (( kj mol -1 ) ( kj mol -1 )) / -298 K = kj K - 1 mol -1 T = ΔH / ΔS = kj mol -1 / kj K -1 mol -1 = K

### Name AP CHEM / / Collected AP Exam Essay Answers for Chapter 16

Name AP CHEM / / Collected AP Exam Essay Answers for Chapter 16 1980 - #7 (a) State the physical significance of entropy. Entropy (S) is a measure of randomness or disorder in a system. (b) From each of

### AP Practice Questions

1) AP Practice Questions The tables above contain information for determining thermodynamic properties of the reaction below. C 2 H 5 Cl(g) + Cl 2 (g) C 2 H 4 Cl 2 (g) + HCl(g) (a) Calculate ΔH for

### Thermodynamics- Chapter 19 Schedule and Notes

Thermodynamics- Chapter 19 Schedule and Notes Date Topics Video cast DUE Assignment during class time One Review of thermodynamics 1_thermo_review AND Review of thermo Wksheet 2.1ch19_intro Optional: 1sc_thermo

### Chapter 20. Thermodynamics p. 811 842. Spontaneity. What have we learned about spontaneity during this course?

Chapter 20 p. 811 842 Spontaneous process: Ex. Nonspontaneous process: Ex. Spontaneity What have we learned about spontaneity during this course? 1) Q vs. K? 2) So.. Spontaneous process occurs when a system

### Standard Free Energies of Formation at 298 K. Average Bond Dissociation Energies at 298 K

1 Thermodynamics There always seems to be at least one free response question that involves thermodynamics. These types of question also show up in the multiple choice questions. G, S, and H. Know what

### The first law: transformation of energy into heat and work. Chemical reactions can be used to provide heat and for doing work.

The first law: transformation of energy into heat and work Chemical reactions can be used to provide heat and for doing work. Compare fuel value of different compounds. What drives these reactions to proceed

### 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

### 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

### 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.

### 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,

### 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

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?

Chapter 18 Homework Answers 18.22. 18.24. 18.26. a. Since G RT lnk, as long as the temperature remains constant, the value of G also remains constant. b. In this case, G G + RT lnq. Since the reaction

### Reading. Spontaneity. Monday, January 30 CHEM 102H T. Hughbanks

Thermo Notes #3 Entropy and 2nd Law of Thermodynamics Monday, January 30 CHEM 102H T. Hughbanks Reading You should reading Chapter 7. Some of this material is quite challenging, be sure to read this material

### Thermodynamics Worksheet I also highly recommend Worksheets 13 and 14 in the Lab Manual

Thermodynamics Worksheet I also highly recommend Worksheets 13 and 14 in the Lab Manual 1. Predict the sign of entropy change in the following processes a) The process of carbonating water to make a soda

### Thermodynamics: First Law, Calorimetry, Enthalpy. Calorimetry. Calorimetry: constant volume. Monday, January 23 CHEM 102H T.

Thermodynamics: First Law, Calorimetry, Enthalpy Monday, January 23 CHEM 102H T. Hughbanks Calorimetry Reactions are usually done at either constant V (in a closed container) or constant P (open to the

### 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

### Energy and Chemical Reactions. Characterizing Energy:

Energy and Chemical Reactions Energy: Critical for virtually all aspects of chemistry Defined as: We focus on energy transfer. We observe energy changes in: Heat Transfer: How much energy can a material

### Thermodynamics and Equilibrium

Chapter 19 Thermodynamics and Equilibrium Concept Check 19.1 You have a sample of 1.0 mg of solid iodine at room temperature. Later, you notice that the iodine has sublimed (passed into the vapor state).

### 1. Thermite reaction 2. Enthalpy of reaction, H 3. Heating/cooling curves and changes in state 4. More thermite thermodynamics

Chem 105 Fri 10-23-09 1. Thermite reaction 2. Enthalpy of reaction, H 3. Heating/cooling curves and changes in state 4. More thermite thermodynamics 10/23/2009 1 Please PICK UP your graded EXAM in front.

### Spontaneity of a Chemical Reaction

Spontaneity of a Chemical Reaction We have learned that entropy is used to quantify the extent of disorder resulting from the dispersal of matter in a system. Also; entropy, like enthalpy and internal

### Sample Exercise 15.1 Writing Equilibrium-Constant Expressions

Sample Exercise 15.1 Writing Equilibrium-Constant Expressions Write the equilibrium expression for K c for the following reactions: Solution Analyze: We are given three equations and are asked to write

### Thermodynamics. Thermodynamics 1

Thermodynamics 1 Thermodynamics Some Important Topics First Law of Thermodynamics Internal Energy U ( or E) Enthalpy H Second Law of Thermodynamics Entropy S Third law of Thermodynamics Absolute Entropy

### Unit 19 Practice. Name: Class: Date: Multiple Choice Identify the choice that best completes the statement or answers the question.

Name: Class: Date: Unit 19 Practice Multiple Choice Identify the choice that best completes the statement or answers the question. 1) The first law of thermodynamics can be given as. A) E = q + w B) =

### vap H = RT 1T 2 = 30.850 kj mol 1 100 kpa = 341 K

Thermodynamics: Examples for chapter 6. 1. The boiling point of hexane at 1 atm is 68.7 C. What is the boiling point at 1 bar? The vapor pressure of hexane at 49.6 C is 53.32 kpa. Assume that the vapor

### 87 16 70 20 58 24 44 32 35 40 29 48 (a) graph Y versus X (b) graph Y versus 1/X

HOMEWORK 5A Barometer; Boyle s Law 1. The pressure of the first two gases below is determined with a manometer that is filled with mercury (density = 13.6 g/ml). The pressure of the last two gases below

### Name AP Chemistry / / Chapter 13 Collected AP Exam Free Response Questions 1980 2010 Answers

Name AP Chemistry / / Chapter 13 Collected AP Exam Free Response Questions 1980 2010 Answers 1980 - #6 NH 4 Cl(s) NH 3 (g) + HCl(g) ΔH = +42.1 kilocalories Suppose the substances in the reaction above

### Spring 2009. kj mol 125 0-229 -92. H f. H rxn = Σ H f (products) - Σ H f (reactants)

Spring 2009 2. The reaction of an elemental halogen with an alkane is a very common reaction. The reaction between chlorine and butane is provided below. (NOTE: Questions a d and f pertain to this reaction.)

### Unit 5 Practice Test. Name: Class: Date: Multiple Choice Identify the choice that best completes the statement or answers the question.

Name: Class: Date: Unit 5 Practice Test Multiple Choice Identify the choice that best completes the statement or answers the question. 1) The internal energy of a system is always increased by. A) adding

### 1 Exercise 2.19a pg 86

In this solution set, an underline is used to show the last significant digit of numbers. For instance in x = 2.51693 the 2,5,1, and 6 are all significant. Digits to the right of the underlined digit,

### Chapter 6 Thermodynamics: The First Law

Key Concepts 6.1 Systems Chapter 6 Thermodynamics: The First Law Systems, States, and Energy (Sections 6.1 6.8) thermodynamics, statistical thermodynamics, system, surroundings, open system, closed system,

### A k 1. At equilibrium there is no net change in [A] or [B], namely d[a] dt

Chapter 15: Chemical Equilibrium Key topics: Equilibrium Constant Calculating Equilibrium Concentrations The Concept of Equilibrium Consider the reaction A k 1 k 1 B At equilibrium there is no net change

### Thermochemistry is study of changes in energy (heat) associated with physical or chemical changes.

Thermochem 1 Thermochemistry Thermochemistry and Energy and Temperature Thermochemistry is study of changes in energy (heat) associated with physical or chemical changes. Force = push F= m a (mass x acceleration)

### SUPPLEMENTARY TOPIC 3 ENERGY AND CHEMICAL REACTIONS

SUPPLEMENTARY TOPIC 3 ENERGY AND CHEMICAL REACTIONS Rearranging atoms. In a chemical reaction, bonds between atoms in one or more molecules (reactants) break and new bonds are formed with other atoms to

### CHEMICAL EQUILIBRIUM (ICE METHOD)

CHEMICAL EQUILIBRIUM (ICE METHOD) Introduction Chemical equilibrium occurs when opposing reactions are proceeding at equal rates. The rate at which the products are formed from the reactants equals the

### Name Class Date. In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.

Assessment Chapter Test A Chapter: States of Matter In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question. 1. The kinetic-molecular

### CHAPTER 12 GASES AND THEIR BEHAVIOR

Chapter 12 Gases and Their Behavior Page 1 CHAPTER 12 GASES AND THEIR BEHAVIOR 12-1. Which of the following represents the largest gas pressure? (a) 1.0 atm (b) 1.0 mm Hg (c) 1.0 Pa (d) 1.0 KPa 12-2. Nitrogen

### Energy Flow in Marine Ecosystem

Energy Flow in Marine Ecosystem Introduction Marin ecosystem is a functional system and consists of living groups and the surrounding environment It is composed of some groups and subgroups 1. The physical

### AP CHEMISTRY 2008 SCORING GUIDELINES (Form B)

AP CHEMISTRY 2008 SCORING GUIDELINES (Form B) Question 6 Use principles of thermodynamics to answer the following questions. (a) The gas N 2 O 4 decomposes to form the gas NO 2 according to the equation

### Introductory Chemistry, 3 rd Edition Nivaldo Tro. Roy Kennedy Massachusetts Bay Community College Wellesley Hills, Maqqwertd ygoijpk[l

Introductory Chemistry, 3 rd Edition Nivaldo Tro Quantities in Car an octane and oxygen molecules and carbon dioxide and water Chemical Reactions Roy Kennedy Massachusetts Bay Community College Wellesley

### INTI COLLEGE MALAYSIA A? LEVEL PROGRAMME CHM 111: CHEMISTRY MOCK EXAMINATION: DECEMBER 2000 SESSION. 37 74 20 40 60 80 m/e

CHM111(M)/Page 1 of 5 INTI COLLEGE MALAYSIA A? LEVEL PROGRAMME CHM 111: CHEMISTRY MOCK EXAMINATION: DECEMBER 2000 SESSION SECTION A Answer ALL EIGHT questions. (52 marks) 1. The following is the mass spectrum

### CHAPTER 14 (MOORE) CHEMICAL EQUILIBRIUM

CHAPTER 14 (MOORE) CHEMICAL EQUILIBRIUM This chapter deals with chemical equilibrium, or how far chemical reactions proceed. Some reactions convert reactants to products with near 100% efficiency but others

### Enthalpy of Reaction and Calorimetry worksheet

Enthalpy of Reaction and Calorimetry worksheet 1. Calcium carbonate decomposes at high temperature to form carbon dioxide and calcium oxide, calculate the enthalpy of reaction. CaCO 3 CO 2 + CaO 2. Carbon

### Test 5 Review questions. 1. As ice cools from 273 K to 263 K, the average kinetic energy of its molecules will

Name: Thursday, December 13, 2007 Test 5 Review questions 1. As ice cools from 273 K to 263 K, the average kinetic energy of its molecules will 1. decrease 2. increase 3. remain the same 2. The graph below

### Entropy Changes & Processes

Entropy Changes & Processes Chapter 4 of Atkins: he Second Law: he Concepts Section 4.3, 7th edition; 3.3, 8th edition Entropy of Phase ransition at the ransition emperature Expansion of the Perfect Gas

### 7. 1.00 atm = 760 torr = 760 mm Hg = 101.325 kpa = 14.70 psi. = 0.446 atm. = 0.993 atm. = 107 kpa 760 torr 1 atm 760 mm Hg = 790.

CHATER 3. The atmosphere is a homogeneous mixture (a solution) of gases.. Solids and liquids have essentially fixed volumes and are not able to be compressed easily. have volumes that depend on their conditions,

### Module 5: Combustion Technology. Lecture 34: Calculation of calorific value of fuels

1 P age Module 5: Combustion Technology Lecture 34: Calculation of calorific value of fuels 2 P age Keywords : Gross calorific value, Net calorific value, enthalpy change, bomb calorimeter 5.3 Calculation

### CHEM 105 HOUR EXAM III 28-OCT-99. = -163 kj/mole determine H f 0 for Ni(CO) 4 (g) = -260 kj/mole determine H f 0 for Cr(CO) 6 (g)

CHEM 15 HOUR EXAM III 28-OCT-99 NAME (please print) 1. a. given: Ni (s) + 4 CO (g) = Ni(CO) 4 (g) H Rxn = -163 k/mole determine H f for Ni(CO) 4 (g) b. given: Cr (s) + 6 CO (g) = Cr(CO) 6 (g) H Rxn = -26

### ENTHALPY CHANGES FOR A CHEMICAL REACTION scaling a rxn up or down (proportionality) quantity 1 from rxn heat 1 from Δ r H. = 32.

CHEMISTRY 103 Help Sheet #10 Chapter 4 (Part II); Sections 4.6-4.10 Do the topics appropriate for your lecture Prepared by Dr. Tony Jacob http://www.chem.wisc.edu/areas/clc (Resource page) Nuggets: Enthalpy

### Thermodynamics. S (reactants) S S (products) AP Chemistry. Period Date / / R e v i e w. 1. Consider the first ionization of sulfurous acid:

AP Chemistry Thermodynamics 1. Consider the first ionization of sulfurous acid: H 2SO 3(aq) H + (aq) + HSO 3 - (aq) Certain related thermodynamic data are provided below: H 2SO 3(aq) H + (aq) HSO 3 - (aq)

### = T T V V T = V. By using the relation given in the problem, we can write this as: ( P + T ( P/ T)V ) = T

hermodynamics: Examples for chapter 3. 1. Show that C / = 0 for a an ideal gas, b a van der Waals gas and c a gas following P = nr. Assume that the following result nb holds: U = P P Hint: In b and c,

### Answers: Given: No. [COCl 2 ] = K c [CO][Cl 2 ], but there are many possible values for [CO]=[Cl 2 ]

Chemical Equilibrium What are the concentrations of reactants and products at equilibrium? How do changes in pressure, volume, temperature, concentration and the use of catalysts affect the equilibrium

### 10 Cl atoms. 10 H2O molecules. 8.3 mol HCN = 8.3 mol N atoms 1 mol HCN. 2 mol H atoms 2.63 mol CH2O = 5.26 mol H atoms 1 mol CH O

Chem 100 Mole conversions and stoichiometry worksheet 1. How many Ag atoms are in.4 mol Ag atoms? 6.0 10 Ag atoms 4.4 mol Ag atoms = 1.46 10 Ag atoms 1 mol Ag atoms. How many Br molecules are in 18. mol

### www.chemsheets.co.uk 17-Jul-12 Chemsheets A2 033 1

www.chemsheets.co.uk 17-Jul-12 Chemsheets A2 033 1 AS THERMODYNAMICS REVISION What is enthalpy? It is a measure of the heat content of a substance Enthalpy change ( H) = Change in heat content at constant

### AP Chemistry 2007 Scoring Guidelines Form B

AP Chemistry 2007 Scoring Guidelines Form B The College Board: Connecting Students to College Success The College Board is a not-for-profit membership association whose mission is to connect students to

### Chapter 13. Chemical Equilibrium

Chapter 13 Chemical Equilibrium Chapter 13 Preview Chemical Equilibrium The Equilibrium condition and constant Chemical equilibrium, reactions, constant expression Equilibrium involving Pressure Chemical

### Chem 1A Exam 2 Review Problems

Chem 1A Exam 2 Review Problems 1. At 0.967 atm, the height of mercury in a barometer is 0.735 m. If the mercury were replaced with water, what height of water (in meters) would be supported at this pressure?

### CHEM 1332 CHAPTER 14

CHEM 1332 CHAPTER 14 1. Which is a proper description of chemical equilibrium? The frequencies of reactant and of product collisions are identical. The concentrations of products and reactants are identical.

### Name Date Class STOICHIOMETRY. SECTION 12.1 THE ARITHMETIC OF EQUATIONS (pages 353 358)

Name Date Class 1 STOICHIOMETRY SECTION 1.1 THE ARITHMETIC OF EQUATIONS (pages 353 358) This section explains how to calculate the amount of reactants required or product formed in a nonchemical process.

### Chapter 1 The Atomic Nature of Matter: Selected Answersc for Practice Exam.

Chapter 1 The Atomic Nature of Matter: Selected Answersc for Practice Exam. MULTIPLE CHOICE 50. 5.80 g of dioxane (C 4 H 8 O 2 ) is how many moles of dioxane? 0.0658 mol 0.0707 mol 0.0725 mol d. 0.0804

### a) Use the following equation from the lecture notes: = ( 8.314 J K 1 mol 1) ( ) 10 L

hermodynamics: Examples for chapter 4. 1. One mole of nitrogen gas is allowed to expand from 0.5 to 10 L reversible and isothermal process at 300 K. Calculate the change in molar entropy using a the ideal

### Thermochemistry. r2 d:\files\courses\1110-20\99heat&thermorans.doc. Ron Robertson

Thermochemistry r2 d:\files\courses\1110-20\99heat&thermorans.doc Ron Robertson I. What is Energy? A. Energy is a property of matter that allows work to be done B. Potential and Kinetic Potential energy

### Moles and Chemical Reactions. Moles and Chemical Reactions. Molar mass = 2 x 12.011 + 6 x 1.008 + 1 x15.999 = 46.069 g/mol

We have used the mole concept to calculate mass relationships in chemical formulas Molar mass of ethanol (C 2 H 5 OH)? Molar mass = 2 x 12.011 + 6 x 1.008 + 1 x15.999 = 46.069 g/mol Mass percentage of

### CHEMICAL EQUILIBRIUM

Chemistry 10 Chapter 14 CHEMICAL EQUILIBRIUM Reactions that can go in both directions are called reversible reactions. These reactions seem to stop before they go to completion. When the rate of the forward

### Reading: Moore chapter 18, sections 18.6-18.11 Questions for Review and Thought: 62, 69, 71, 73, 78, 83, 99, 102.

Thermodynamics 2: Gibbs Free Energy and Equilibrium Reading: Moore chapter 18, sections 18.6-18.11 Questions for Review and Thought: 62, 69, 71, 73, 78, 83, 99, 102. Key Concepts and skills: definitions

### Chemical Equilibrium

Chapter 13 Chemical Equilibrium Equilibrium Physical Equilibrium refers to the equilibrium between two or more states of matter (solid, liquid and gas) A great example of physical equilibrium is shown

### CHEM1612 2014-N-2 November 2014

CHEM1612 2014-N-2 November 2014 Explain the following terms or concepts. Le Châtelier s principle 1 Used to predict the effect of a change in the conditions on a reaction at equilibrium, this principle

### Equilibrium Lecture #1. Schweitzer

Equilibrium Lecture #1 Schweitzer What is equilibrium? Remember Equilibrium process between to competing reactions. At equilibrium the forward process is equal to the reverse process. *** It appears that

### 1. What is the molecular formula of a compound with the empirical formula PO and a gram-molecular mass of 284 grams?

Name: Tuesday, May 20, 2008 1. What is the molecular formula of a compound with the empirical formula PO and a gram-molecular mass of 284 grams? 2 5 1. P2O 5 3. P10O4 2. P5O 2 4. P4O10 2. Which substance

### The value of a state function is independent of the history of the system.

1 THERMODYNAMICS - The study of energy in matter - Thermodynamics allows us to predict whether a chemical reaction occurs or not. - Thermodynamics tells us nothing about how fast a reaction occurs. - i.

### CHEM 36 General Chemistry EXAM #1 February 13, 2002

CHEM 36 General Chemistry EXAM #1 February 13, 2002 Name: Serkey, Anne INSTRUCTIONS: Read through the entire exam before you begin. Answer all of the questions. For questions involving calculations, show

### Thermodynamics. Chapter 13 Phase Diagrams. NC State University

Thermodynamics Chapter 13 Phase Diagrams NC State University Pressure (atm) Definition of a phase diagram A phase diagram is a representation of the states of matter, solid, liquid, or gas as a function

### Problem # 2 Determine the kinds of intermolecular forces present in each element or compound:

Chapter 11 Homework solutions Problem # 2 Determine the kinds of intermolecular forces present in each element or compound: A. Kr B. NCl 3 C. SiH 4 D. HF SOLUTION: Kr is a single atom, hence it can have

### Problem Solving. Stoichiometry of Gases

Skills Worksheet Problem Solving Stoichiometry of Gases Now that you have worked with relationships among moles, mass, and volumes of gases, you can easily put these to work in stoichiometry 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

### PV (0.775 atm)(0.0854 L) n = = = 0.00264 mol RT -1-1

catalyst 2 5 g ¾¾¾¾ 2 4 g 2 g DH298 = rxn DS298 C H OH( ) C H ( ) + H O( ) 45.5 kj/mol ; = 126 J/(K mol ) ethanol ethene water rxn 1 atm 760 torr PV (0.775 atm)(0.0854 L) n = = = 0.00264 mol RT -1-1 (0.08206

### 2. The percent yield is the maximum amount of product that can be produced from the given amount of limiting reactant.

UNIT 6 stoichiometry practice test True/False Indicate whether the statement is true or false. moles F 1. The mole ratio is a comparison of how many grams of one substance are required to participate in

### Chemistry B11 Chapter 4 Chemical reactions

Chemistry B11 Chapter 4 Chemical reactions Chemical reactions are classified into five groups: A + B AB Synthesis reactions (Combination) H + O H O AB A + B Decomposition reactions (Analysis) NaCl Na +Cl

### Thermodynamics Experiment The Enthalpy of H 2 O 2 Decomposition in Aqueous Solution

Thermodynamics Experiment The Enthalpy of H 2 O 2 Decomposition in Aqueous Solution OBJECTIVES 1. To illustrate the use of calorimetry in the experimental measurement of thermodynamic data. 2. To illustrate

### CHM111 Lab Enthalpy of Hydration of Sodium Acetate Grading Rubric

Name Team Name CHM111 Lab Enthalpy of Hydration of Sodium Acetate Grading Rubric Criteria Points possible Points earned Lab Performance Printed lab handout and rubric was brought to lab 3 Safety and proper

### Final Exam CHM 3410, Dr. Mebel, Fall 2005

Final Exam CHM 3410, Dr. Mebel, Fall 2005 1. At -31.2 C, pure propane and n-butane have vapor pressures of 1200 and 200 Torr, respectively. (a) Calculate the mole fraction of propane in the liquid mixture

### IB Chemistry. DP Chemistry Review

DP Chemistry Review Topic 1: Quantitative chemistry 1.1 The mole concept and Avogadro s constant Assessment statement Apply the mole concept to substances. Determine the number of particles and the amount

### Calculations with Chemical Reactions

Calculations with Chemical Reactions Calculations with chemical reactions require some background knowledge in basic chemistry concepts. Please, see the definitions from chemistry listed below: Atomic

### Chapter 4 Practice Quiz

Chapter 4 Practice Quiz 1. Label each box with the appropriate state of matter. A) I: Gas II: Liquid III: Solid B) I: Liquid II: Solid III: Gas C) I: Solid II: Liquid III: Gas D) I: Gas II: Solid III:

### Chapter 13. Chemical Equilibrium

Chapter 13 Chemical Equilibrium Section 13.1 The Equilibrium Condition Section 13.1 The Equilibrium Condition Section 13.1 The Equilibrium Condition Section 13.1 The Equilibrium Condition Section 13.1

### Calorimetry and Enthalpy. Chapter 5.2

Calorimetry and Enthalpy Chapter 5.2 Heat Capacity Specific heat capacity (c) is the quantity of thermal energy required to raise the temperature of 1g of a substance by 1⁰C The units for specific heat

### Chemical Thermodynamics

Chemical Thermodynamics David A. Katz Department of Chemistry Pima Community College Tucson, AZ 85709, USA First Law of Thermodynamics The First Law of Thermodynamics was expressed in the study of thermochemistry.

### 1. solid, vapor, critical point correct. 2. solid, liquid, critical point. 3. liquid, vapor, critical point. 4. solid, liquid, triple point

mcdonald (pam78654) HW 7B: Equilibria laude (89560) 1 This print-out should have 18 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0

### Chapter 8 Basic Concepts of Chemical Bonding

Chapter 8 Basic Concepts of Chemical Bonding Why do TiCl 4 and TiCl 3 have different colors?... different chemical properties?... different physical states? Chemical Bonding and Properties Difference in

### AP* Chemistry CHEMICAL EQUILIBRIA: GENERAL CONCEPTS

AP* Chemistry CHEMICAL EQUILIBRIA: GENERAL CONCEPTS THE NATURE OF THE EQUILIBRIUM STATE: Equilibrium is the state where the rate of the forward reaction is equal to the rate of the reverse reaction. At

### AS1 MOLES. oxygen molecules have the formula O 2 the relative mass will be 2 x 16 = 32 so the molar mass will be 32g mol -1

Moles 1 MOLES The mole the standard unit of amount of a substance the number of particles in a mole is known as Avogadro s constant (L) Avogadro s constant has a value of 6.023 x 10 23 mol -1. Example

### Calorimeter: A device in which the heat associated with a specific process is measured.

1 CALORIMETRY p. 661-667 (simple), 673-675 (bomb) Calorimeter: A device in which the heat associated with a specific process is measured. There are two basic types of calorimeters: 1. Constant-pressure

### Chemistry 110 Lecture Unit 5 Chapter 11-GASES

Chemistry 110 Lecture Unit 5 Chapter 11-GASES I. PROPERITIES OF GASES A. Gases have an indefinite shape. B. Gases have a low density C. Gases are very compressible D. Gases exert pressure equally in all

### Molecular Formula: Example

Molecular Formula: Example A compound is found to contain 85.63% C and 14.37% H by mass. In another experiment its molar mass is found to be 56.1 g/mol. What is its molecular formula? 1 CHAPTER 3 Chemical

### UNIT 1 THERMOCHEMISTRY

UNIT 1 THERMOCHEMISTRY THERMOCHEMISTRY LEARNING OUTCOMES Students will be expected to: THERMOCHEMISTRY STSE analyse why scientific and technological activities take place in a variety individual and group

### Energy/Reaction Coordinate Diagrams Thermodynamics, Kinetics Dr. Ron Rusay. Entropy (ΔS) A Reaction Coordinate (Energy) Diagram

A Reaction Coordinate (Energy) Diagram Energy/Reaction Coordinate Diagrams Thermodynamics, Kinetics Dr. Ron Rusay Thermodynamic Quantities ΔG o = ΔH o - TΔS o ΔG,ΔH,ΔS, ΔE are state functions ΔE = q +

### Thermodynamics explores the connection between energy and the EXTENT of a reaction but does not give information about reaction rates (Kinetics).

Thermodynamics explores the connection between energy and the EXTENT of a reaction but does not give information about reaction rates (Kinetics). Rates of chemical reactions are controlled by activation