# STOICHIOMETRY. - the study of the quantitative aspects of chemical

Save this PDF as:

Size: px
Start display at page:

## Transcription

1 STOICHIOMETRY - the study of the quantitative aspects of chemical

2 GENERAL PLAN FOR STOICHIOMETRY Mass reactant Mass product Moles reactant Stoichiometric factor Moles product

3 STOICHIOMETRY It rests on the principle of the conservation 2 Al(s) + 3 Br 2 (liq) f Al 2 Br 6 (s)

4 Conversion Factors from Eqns The mole ratio between two species, as given in the balanced chemical equation, is the PER expression that links moles of one species to moles of another:

5 Conversion Factors from Eqns Example: How many moles of oxygen are needed to completely react with 2.34 moles of ammonia in a reaction that yields nitrogen monoxide and water? Solution: First, write and balance the chemical

6 Conversion Factors from Eqns How many moles of oxygen are needed to completely react with 2.34 moles of ammonia in a reaction that yields nitrogen monoxide and water? 4 NH O 2 4 NO + 6 H 2 O The PER relationship comes from the balanced equation:

7 Conversion Factors from Eqns GIVEN: 2.34 mol NH 3, 4 NH O 2 4 NO + 6 H 2 O WANTED: mol O 2 PER:

8 Mass-Mass Stoichiometry Goal 2 Given a chemical equation, or a reaction for which the equation can be written, and the number of grams or moles of one species in the reaction, find the number of grams or moles of any other species.

9 Mass-Mass Stoichiometry Stoichiometry The quantitative relationships among substances involved in a chemical reaction. Established by the balanced equation for the reaction. A stoichiometry problem asks, How much or how many?

10 Mass Mass Stoichiometry Prerequisite Skills for Stoichiometry Write chemical formulas. Ch. 6 Calculate molar masses from chemical formulas. Sect. 7.4 Use molar masses to convert between moles and mass. Sect. 7.5 Write and balance chemical equations. Ch. 8 Use an equation to convert from moles

11 Mass Mass Stoichiometry Mass-to-Mass Stoichiometry Path Mass of Moles of Moles of Mass of Given Given Wanted Wanted Molar Mass Equation Molar Mass g PER mol mol PER mol g PER mol Mass Given

12 Mass Mass Stoichiometry How to Solve a Stoichiometry Problem: The Stoichiometry Path Step 1: Change the mass of the given species to moles. Step 2: Change the moles of the given species to the moles of the wanted species. Step 3: Change the moles of the wanted species

13 Mass Mass Stoichiometry Example: How many grams of carbon dioxide are produced when 10.0 g of methane, CH 4, is burned? Solution: GIVEN: 10.0 g CH 4 WANTED: g CO 2 CH O 2 CO H 2 O PER: g CH 4 /mol CH 4 PATH: g CH 4 mol CH 4 1 mol CO 2 /1 mol CH g CO 2 /mol CO 2

14 Mass Mass Stoichiometry 10.0 g CH 4 = 27.4 g CO 2

15 Percent Yield Goal 3 Given two of the following, or information from which two of the following may be determined, calculate the third: theoretical yield, actual yield, percent yield. Theoretical Yield = Maximum amount of product possible based on amount of reactant(s). Actual Yield = How much product was actually obtained.

16 Percent Yield The actual yield of a chemical reaction is usually less than the theoretical yield predicted by a stoichiometry calculation because: reactants may be impure the reaction may not go to completion other reactions may occur Actual yield is experimentally determined.

17 Percent Yield Percent yield expresses the ratio of actual yield to theoretical yield: % yield = 100

18 Percent Yield Example: Determine the percent yield if 6.97 grams of ammonia is produced from the reaction of 6.22 grams of nitrogen with excess hydrogen. Solution: Notice that two quantities are given in the problem statement g NH 3 is the actual yield 6.22 g N 2 is the amount of reactant. This can be used to

19 Percent Yield GIVEN: 6.22 g N 2 WANTED: g NH 3 (theo) N H 2 2 NH 3 PER: g N 2 /mol N 2 2 mol NH 3 /1 mol N 2 PATH: g N 2 mol N 2

20 Percent Yield 6.22 g N 2 = 7.56 g NH 3 (theo) % yield = 100 = 100 =

21 Percent Yield Once a percent yield has been determined for a reaction, it can be used in stoichiometry calculations. For example, the 92.2% yield from the prior example means: and

22 PROBLEM: If 454 g of NH 4 NO 3 decomposes, how much N 2 O and H 2 O are formed? What is the theoretical yield of products? STEP 1 Write the balanced chemical equation NH 4 NO 3 (s) f N 2 O(g) + 2 H 2 O(g)

23 454 g of NH 4 NO 3 f N 2 O + 2 H 2 O STEP 2 Convert mass of reactant (454 g) to amount (mol) STEP 3 Convert amount of reactant (5.67 mol) to amount (mol) of product.

24 454 g of NH 4 NO 3 f N 2 O + 2 H 2 O STEP 3 Convert moles reactant f moles product Relate moles NH 4 NO 3 to moles product expected. 1 mol NH 4 NO 3 f 2 mol H 2 O Express this relation as the STOICHIOMETRIC FACTOR

25 454 g of NH 4 NO 3 f N 2 O + 2 H 2 O STEP 3 Convert moles reactant (5.67 mol) to amount (mol) of product = 11.3 mol H 2 O produced

26 454 g of NH 4 NO 3 f N 2 O + 2 H 2 O STEP 4 Convert amount of product (11.3 mol) to mass of product Called the THEORETICAL YIELD ALWAYS FOLLOW THESE STEPS IN SOLVING STOICHIOMETRY PROBLEMS!

27 454 g of NH 4 NO 3 f N 2 O + 2 H 2 O STEP 5 What mass of N 2 O is formed? Total mass of reactants = total mass of products 454 g NH 4 NO 3 = g N 2 O g H 2 O

28 454 g of NH 4 NO 3 f N 2 O + 2 H 2 O Amounts Table (from page 159) 1.Compound NH 4 NO 3 N 2 O H 2 O 2. Initial (g) 3. Initial (mol) 4. Change (mol) 5. Final (mol) 6. Final (g)

29 454 g of NH 4 NO 3 f N 2 O + 2 H 2 O Amounts Table 1.Compound NH 4 NO 3 N 2 O H 2 O 2.Initial (g) 454 g Initial (mol)5.67 mol Change (mol) (5.67) 5.Final (mol) Final (g) Note that matter is conserved!

30 454 g of NH 4 NO 3 f N 2 O + 2 H 2 O STEP 6 Calculate the percent yield If you isolated only 131 g of N 2 O, what is the percent yield? This compares the theoretical (250.

31 454 g of NH 4 NO 3 f N 2 O + 2 H 2 O STEP 6 Calculate the percent yield

32 PROBLEM: Using 5.00 g of H 2 O 2, what mass of O 2 and of H 2 O can be obtained? 2 H 2 O 2 (liq) f 2 H 2 O(g) + O 2 (g) Reaction is catalyzed by MnO 2 Step 1: amount (mol) of H 2 O 2 Step 2: use STOICHIOMETRIC FACTOR to calculate amount (mol) of O 2

33 Reactions Involving a LIMITING REACTANT 1.In a given reaction, there is not enough of one reagent to use up the other reagent completely. 2.The reagent in short supply LIMITS the quantity of product that can be formed.

34 LIMITING REACTANTS Reactants Products 2 NO(g) + O 2 (g) f 2 NO 2 (g) Limiting reactant = Excess reactant =

35 LIMITING REACTANTS React solid Zn with mol HCl (aq) Zn + 2 HCl f ZnCl 2 + H 2 PLAY MOVIE Rxn 1: Balloon inflates fully, some Zn left * More than enough Zn to use up the mol HCl Rxn 2: Balloon inflates fully, no Zn left * Right amount of each (HCl and Zn) Rxn 3: Balloon does not inflate fully, no Zn left.

36 LIMITING REACTANTS React solid Zn with mol HCl (aq) Zn + 2 HCl f ZnCl 2 + H mol HCl [1 mol Zn/2 mol HCl] = mol Zn Rxn 1 Rxn 2 Rxn 3 mass Zn (g) mol Zn

37 Limiting Reactants Goal 4 Identify and describe or explain limiting reactants and excess reactants.

38 Limiting Reactants Three atoms of carbon react with two molecules of oxygen:

39 Limiting Reactants The reaction will stop when two molecules of oxygen are used up. Two carbon dioxide molecules will form; One carbon atom will remain unreacted: C + O 2 CO 2 Start Used (+) or Produced ( )

40 Limiting Reactants Limiting Reactant The reactant that is completely used up. (Oxygen) Excess Reactant The reactant initially present in excess. (some will remain unreacted) (Carbon)

41 Limiting Reactants Goal 5 Given a chemical equation, or information from which it may be determined, and initial quantities of two or more reactants, (a) identify the limiting reactant, (b) calculate the theoretical yield of a specified product, assuming complete use of the limiting reactant, and (c) calculate the quantity of reactant initially in excess that remains unreacted.

42 Limiting Reactants Comparison-of-Moles Method How to Solve a Limiting Reactant Problem: 1. Convert the number of grams of each reactant to moles. 2. Identify the limiting reactant. 3. Calculate the number of moles of each species that reacts or is produced. 4. Calculate the number of moles of each species that remains after the reaction. 5. Change the number of moles of each species to grams.

43 Limiting Reactants Example: A 24.0-g piece of solid sodium is added to 24.0 g of liquid water. How many grams of hydrogen will be produced? How many grams of which reactant will be left over? Solution: Step 1 is to convert the number of grams of each reactant to moles g Na = 1.04 mol Na

44 Limiting Reactants Step 2 is to identify the limiting reactant. This requires a balanced chemical equation so that the mole ratio of the reacting substances can be identified. 2 Na + 2 H 2 O H NaOH For every 2 mol of Na that react, 2 mol of H 2 O react, a 2:2 or 1:1 ratio. Thus, the 1.04 mol Na will be the limiting reactant.

45 Limiting Reactants Step 3 is to calculate the number of moles of each species that reacts or is produced. This can be done by assembling the data into a table. 2 Na + NaOH 2 H 2 O H 2 +2 Grams at start Molar mass, g/mol Moles at start Moles used ( ),

46 Limiting Reactants Step 4 is to calculate the number of moles of each species that remains after the reaction. 2 Na + 2 H 2 O H NaOH Grams at start Molar mass, g/mol Moles at start

47 Limiting Reactants Step 5 is to change the number of moles of each species to grams. 2 Na + 2 H 2 O H NaOH Moles at end mol H 2 O = 5.2 g H 2 O 0.52 mol H 2 = 1.0 g H 2

48 Limiting Reactants Returning to the original problem statement: A 24.0-g piece of solid sodium is added to 24.0 g of liquid water. How many grams of hydrogen will be produced? How many grams of which reactant will be left over? The questions can now be answered: 1.0 g H 2 is produced

49 Limiting Reactants Goal 5 Given a chemical equation, or information from which it may be determined, and initial quantities of two or more reactants, (a) identify the limiting reactant, (b) calculate the theoretical yield of a specified product, assuming complete use of the limiting reactant, and (c) calculate the quantity of reactant initially in excess that remains unreacted.

50 Limiting Reactants Smaller-Amount Method How to Solve a Limiting Reactant Problem: 1. Calculate the amount of product that can be formed by the initial amount of each reactant. a) The reactant that yields the smaller amount of product is the limiting reactant. b) The smaller amount of product is the amount that will be formed when all of the limiting reactant is used up. 2. Calculate the amount of excess reactant that is used by the total amount of limiting reactant. 3. Subtract from the amount of excess reactant present initially the amount that is used by all of

51 Limiting Reactants Example: A 24.0-g piece of solid sodium is added to 24.0 g of liquid water. How many grams of hydrogen will be produced? How many grams of which reactant will be left over? Solution: Step 1 is to calculate the amount of product that can be formed by the initial amount of each reactant.

52 Limiting Reactants GIVEN: 24.0 g Na WANTED: g H 2 2 Na + 2 H 2 O H NaOH 24.0 g Na = 1.05 g H 2 GIVEN: 24.0 g H 2 O WANTED: g H g H 2 O

53 Limiting Reactants 24.0 g Na and excess H 2 O produces 1.05 g H g H 2 O and excess Na produces 1.34 g H 2 Step 1a: The reactant that yields the smallest amount of product is the limiting reactant, so Na is the limiting reactant. Step 1b: The smaller amount of product is the amount that will be formed when all of the limiting reactant is

54 Limiting Reactants Step 2 is to calculate the amount of excess reactant that is used by the total amount of limiting reactant. The total amount of limiting reactant is 24.0 g Na. The excess reactant is H 2 O. GIVEN: 24.0 g Na WANTED: g H 2 O 2 Na + 2 H 2 O H NaOH

55 Limiting Reactants Step 3 is to subtract from the amount of excess reactant present initially the amount that is used by all of the limiting reactant. The difference is the amount of excess reactant left g H 2 O initially 18.8 g H 2 O reacted

56 Reaction to be Studied 2 Al(s) + 3 Cl 2 (g) f Al 2 Cl 6 (s)

57 PROBLEM: Mix 5.40 g of Al with 8.10 g of Cl 2. What mass of Al 2 Cl 6 can form? Mass reactant Mass product Moles reactant Stoichiometric factor Moles product

58 Step 1 of LR problem: compare actual mole ratio of reactants to theoretical mole ratio. 2 Al(s) + 3 Cl 2 (g) f Al 2 Cl 6 (s) Reactants must be in the mole

59 Step 2 of LR problem: Calculate moles of each reactant We have 5.40 g of Al and 8.10 g of Cl 2

60 Find mole ratio of reactants 2 Al(s) + 3 Cl 2 (g) f Al 2 Cl 6 (s) mol Al x = mol Cl 2 2.needed to react with mol Al, but we only have mole of Cl 2, so Limiting reactant is Cl 2

61 Mix 5.40 g of Al with 8.10 g of Cl 2. What mass of Al 2 Cl 6 can form? 2 Al(s) + 3 Cl 2 (g) f Al 2 Cl 6 (s) Limiting reactant = Cl 2 Base all calcs. on Cl 2 mass Cl 2 mass Al 2 Cl 6 moles Cl 2 moles Al 2 Cl 6

62 CALCULATIONS: calculate mass of Al 2 Cl 6 expected. Step 1: Calculate moles of Al 2 Cl 6 expected based on LR. Step 2: Calculate mass of Al 2 Cl 6 expected based on LR.

63 How much of which reactant will remain when reaction is complete? 1.Cl 2 was the limiting reactant. Therefore, Al was present in excess. But how much? 2. First find how much Al was required.

64 Calculating Excess Al 2 Al + 3 Cl 2 products mol mol = LR Excess Al = Al available - Al required = mol mol = mol Al in excess

65 Energy Goal 6 Given energy in one of the following units, calculate the other three: joules, kilojoules, calories, and kilocalories.

66 Energy Energy The ability to do work or transfer heat. Energy Unit: Joule Joule (J) The amount of energy exerted when a force of one newton (force required to cause a mass of 1 kg to accelerate at a rate of 1 m/s 2 ) is applied over a displacement of one meter: 1 joule = 1 newton 1 meter 1 J = 1 kg m 2 /sec 2

67 Energy Energy Unit: Calorie calorie (historical definition): Amount of energy required to raise the temperature of 1 g of water by 1 C. calorie (modern definition) 1 cal J A food Calorie (Cal) is a thermochemical kilocalorie. In scientific writing it is capitalized; in everyday writing, interpret the context. 1 kcal = kj

68 Energy Example: How many joules are equivalent to food Calories? Solution: A food Calorie is a thermochemical kilocalorie. GIVEN: kcal WANTED: J PER: 1000 cal/kcal J/cal PATH: kcal cal J

69 Thermochemical Equations Goal 7 Given a chemical equation, or information from which it may be written, and the heat (enthalpy) of reaction, write the thermochemical equation either (a) with H to the right of the conventional equation or (b) as a reactant or product.

70 Thermochemical Equations Enthalpy Heat content of a system. Symbol: H H is the enthalpy of reaction, or, as chemists commonly call it, the heat of reaction. means change in : It is determined by subtracting the initial quantity from the final quantity: A = final value of A initial value of A

71 Thermochemical Equations Enthalpy of Reaction, H If the final heat content of a system is less than its initial heat content, H is negative, and the change is exothermic. If the final heat content of a system is greater than its initial heat content, H is positive, and the change is endothermic.

72 Thermochemical Equations Thermochemical Equation A conventional equation plus its associated H term. Thermochemical equations are typically written in one of two different ways, depending on the context for which it is needed. Example: When one mole of acetylene gas reacts with two moles of hydrogen gas, one mole of ethane gas is formed and 311 kj of energy is released. Write the thermochemical equation in two forms. Solution: C 2 H 2 (g) + 2 H 2 (g) C 2 H 6 (g) kj C 2 H 2 (g) + 2 H 2 (g) C 2 H 6 (g) H = 311 kj

73 Thermochem Stoichiometry Goal 8 Given a thermochemical equation, or information from which it may be written, calculate the amount of energy released or added for a given amount of reactant or product; alternately, calculate the mass of reactant required to produce a given amount of energy.

74 Thermochem Stoichiometry The energy term in a thermochemical equation is directly proportional to the number of moles of all species in the reaction. C 2 H 2 (g) + 2 H 2 (g) C 2 H 6 (g) kj 311 kj 1 mol C 2 H 2

75 Thermochem Stoichiometry

76 Thermochem Stoichiometry Example: When propane, C 3 H 8 (g), is burned to form gaseous carbon dioxide and liquid water, kj of heat is released for every mole of propane burned. What quantity of heat is released when g of propane is burned? Solution: First, write and balance the thermochemical equation to determine the stoichiometric relationships.

77 Thermochem Stoichiometry GIVEN: g C 3 H 8 WANTED: quantity of heat (assume kj) PER: 1 mol C 3 H 8 /44.09 g C 3 H 8 PATH: g C 3 H 8 C 3 H 8 mol kj/1 mol C 3 H 8 kj

### Sample Problem: STOICHIOMETRY and percent yield calculations. How much H 2 O will be formed if 454 g of. decomposes? NH 4 NO 3 N 2 O + 2 H 2 O

STOICHIOMETRY and percent yield calculations 1 Steps for solving Stoichiometric Problems 2 Step 1 Write the balanced equation for the reaction. Step 2 Identify your known and unknown quantities. Step 3

### Chapter 3: Stoichiometry

Chapter 3: Stoichiometry Key Skills: Balance chemical equations Predict the products of simple combination, decomposition, and combustion reactions. Calculate formula weights Convert grams to moles and

### Calculating Atoms, Ions, or Molecules Using Moles

TEKS REVIEW 8B Calculating Atoms, Ions, or Molecules Using Moles TEKS 8B READINESS Use the mole concept to calculate the number of atoms, ions, or molecules in a sample TEKS_TXT of material. Vocabulary

### 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

### Chapter 3: STOICHIOMETRY: MASS, FORMULAS, AND REACTIONS

Chapter 3: STOICHIOMETRY: MASS, FORMULAS, AND REACTIONS Problems: 3.1-3.8, 3.11, 3.14-3.90, 3.103-3.120, 3.122-3.125, 3.128-3.131, 3.134, 3.137-36.138, 3.140-3.142 3.2 THE MOLE Stoichiometry (STOY-key-OM-e-tree):

### 2 Stoichiometry: Chemical Arithmetic Formula Conventions (1 of 24) 2 Stoichiometry: Chemical Arithmetic Stoichiometry Terms (2 of 24)

Formula Conventions (1 of 24) Superscripts used to show the charges on ions Mg 2+ the 2 means a 2+ charge (lost 2 electrons) Subscripts used to show numbers of atoms in a formula unit H 2 SO 4 two H s,

### 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 6 Chemical Calculations

Chapter 6 Chemical Calculations 1 Submicroscopic Macroscopic 2 Chapter Outline 1. Formula Masses (Ch 6.1) 2. Percent Composition (supplemental material) 3. The Mole & Avogadro s Number (Ch 6.2) 4. Molar

### Chemical Equations & Stoichiometry

Chemical Equations & Stoichiometry Chapter Goals Balance equations for simple chemical reactions. Perform stoichiometry calculations using balanced chemical equations. Understand the meaning of the term

### 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

### 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

### Chemical calculations

Chemical calculations Stoichiometry refers to the quantities of material which react according to a balanced chemical equation. Compounds are formed when atoms combine in fixed proportions. E.g. 2Mg +

### 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,

### 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

### 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

### The Mole Concept. The Mole. Masses of molecules

The Mole Concept Ron Robertson r2 c:\files\courses\1110-20\2010 final slides for web\mole concept.docx The Mole The mole is a unit of measurement equal to 6.022 x 10 23 things (to 4 sf) just like there

### Chapter 3. Chemical Reactions and Reaction Stoichiometry. Lecture Presentation. James F. Kirby Quinnipiac University Hamden, CT

Lecture Presentation Chapter 3 Chemical Reactions and Reaction James F. Kirby Quinnipiac University Hamden, CT The study of the mass relationships in chemistry Based on the Law of Conservation of Mass

### Chapter 3. Stoichiometry: Ratios of Combination. Insert picture from First page of chapter. Copyright McGraw-Hill 2009 1

Chapter 3 Insert picture from First page of chapter Stoichiometry: Ratios of Combination Copyright McGraw-Hill 2009 1 3.1 Molecular and Formula Masses Molecular mass - (molecular weight) The mass in amu

### Chem 1100 Chapter Three Study Guide Answers Outline I. Molar Mass and Moles A. Calculations of Molar Masses

Chem 1100 Chapter Three Study Guide Answers Outline I. Molar Mass and Moles A. Calculations of Molar Masses B. Calculations of moles C. Calculations of number of atoms from moles/molar masses 1. Avagadro

### Stoichiometry. Lecture Examples Answer Key

Stoichiometry Lecture Examples Answer Key Ex. 1 Balance the following chemical equations: 3 NaBr + 1 H 3 PO 4 3 HBr + 1 Na 3 PO 4 2 C 3 H 5 N 3 O 9 6 CO 2 + 3 N 2 + 5 H 2 O + 9 O 2 2 Ca(OH) 2 + 2 SO 2

### Mass and Moles of a Substance

Chapter Three Calculations with Chemical Formulas and Equations Mass and Moles of a Substance Chemistry requires a method for determining the numbers of molecules in a given mass of a substance. This allows

### Is it still balanced? Has anything changed? What does it mean? Is it still balanced? Has anything changed? What does it mean?

Chemistry 11 Unit VII Stoichiometry Introduction: Let s look at the following equation 2 H 2 + O 2 2 H 2 O The numbers in front of the H 2 and H 2 O are called coefficients. What do they tell us? They

### Part One: Mass and Moles of Substance. Molecular Mass = sum of the Atomic Masses in a molecule

CHAPTER THREE: CALCULATIONS WITH CHEMICAL FORMULAS AND EQUATIONS Part One: Mass and Moles of Substance A. Molecular Mass and Formula Mass. (Section 3.1) 1. Just as we can talk about mass of one atom of

### Chapter 4: Chemical and Solution Stoichiometry

Chapter 4: Chemical and Solution Stoichiometry (Sections 4.1-4.4) 1 Reaction Stoichiometry The coefficients in a balanced chemical equation specify the relative amounts in moles of each of the substances

### 1. How many hydrogen atoms are in 1.00 g of hydrogen?

MOLES AND CALCULATIONS USING THE MOLE CONCEPT INTRODUCTORY TERMS A. What is an amu? 1.66 x 10-24 g B. We need a conversion to the macroscopic world. 1. How many hydrogen atoms are in 1.00 g of hydrogen?

### Stoichiometry. What is the atomic mass for carbon? For zinc?

Stoichiometry Atomic Mass (atomic weight) Atoms are so small, it is difficult to discuss how much they weigh in grams We use atomic mass units an atomic mass unit (AMU) is one twelfth the mass of the catbon-12

### Ca 3 N 2 (s) + 6H 2 O(l) H 2NH 3 (g) + 3Ca(OH) 2 (s) mole ratio 1 : 6 : 2 : 3 molar mass (g/mole)

1. STOICHIOMETRY INVOLVING ONLY PURE SUBSTANCES For all chemical reactions, the balanced chemical equation gives the mole ratios of reactants and products. If we are dealing with pure chemicals, the molar

### Balance the following equation: KClO 3 + C 12 H 22 O 11 KCl + CO 2 + H 2 O

Balance the following equation: KClO 3 + C 12 H 22 O 11 KCl + CO 2 + H 2 O Ans: 8 KClO 3 + C 12 H 22 O 11 8 KCl + 12 CO 2 + 11 H 2 O 3.2 Chemical Symbols at Different levels Chemical symbols represent

### 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.

### Chapter 8: Quantities in Chemical Reactions

Ch 8 Page 1 Chapter 8: Quantities in Chemical Reactions Stoichiometry: the numerical relationship between chemical quantities in a balanced chemical equation. Ex. 4NH 3 + 5O 2 4NO + 6H 2 O The reaction

### 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

### Chapter 3 Stoichiometry: Calculations with Chemical Formulas and Equations

CHE11 Chapter Chapter Stoichiometry: Calculations with Chemical Formulas and Equations 1. When the following equation is balanced, the coefficients are. NH (g) + O (g) NO (g) + H O (g) (a). 1, 1, 1, 1

### 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

### Moles. Balanced chemical equations Molar ratios Mass Composition Empirical and Molecular Mass Predicting Quantities Equations

Moles Balanced chemical equations Molar ratios Mass Composition Empirical and Molecular Mass Predicting Quantities Equations Micro World atoms & molecules Macro World grams Atomic mass is the mass of an

### 1. P 2 O 5 2. P 5 O 2 3. P 10 O 4 4. P 4 O 10

Teacher: Mr. gerraputa Print Close Name: 1. A chemical formula is an expression used to represent 1. mixtures, only 3. compounds, only 2. elements, only 4. compounds and elements 2. What is the total number

### 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

### 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

### Practice questions for Chapter 8

Practice questions for Chapter 8 2) How many atoms of nickel equal a mass of 58.69 g? (Refer to the Periodic Table.) A) 1 B) 28 C) 58.69 D) 59 E) 6.02 x 1023 Answer: E Section: 8.1 Avogadro's Number 6)

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?

### 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

### 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

### Unit 2: Quantities in Chemistry

Mass, Moles, & Molar Mass Relative quantities of isotopes in a natural occurring element (%) E.g. Carbon has 2 isotopes C-12 and C-13. Of Carbon s two isotopes, there is 98.9% C-12 and 11.1% C-13. Find

### Chem 31 Fall 2002. Chapter 3. Stoichiometry: Calculations with Chemical Formulas and Equations. Writing and Balancing Chemical Equations

Chem 31 Fall 2002 Chapter 3 Stoichiometry: Calculations with Chemical Formulas and Equations Writing and Balancing Chemical Equations 1. Write Equation in Words -you cannot write an equation unless you

### The Mole and Molar Mass

The Mole and Molar Mass 1 Molar mass is the mass of one mole of a substance. Molar mass is numerically equal to atomic mass, molecular mass, or formula mass. However the units of molar mass are g/mol.

### 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

### 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

### Unit 10A Stoichiometry Notes

Unit 10A Stoichiometry Notes Stoichiometry is a big word for a process that chemist s use to calculate amounts in reactions. It makes use of the coefficient ratio set up by balanced reaction equations

### 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

### Other Stoich Calculations A. mole mass (mass mole) calculations. GIVEN mol A x CE mol B. PT g A CE mol A MOLE MASS :

Chem. I Notes Ch. 12, part 2 Using Moles NOTE: Vocabulary terms are in boldface and underlined. Supporting details are in italics. 1 MOLE = 6.02 x 10 23 representative particles (representative particles

### Calculations and Chemical Equations. Example: Hydrogen atomic weight = 1.008 amu Carbon atomic weight = 12.001 amu

Calculations and Chemical Equations Atomic mass: Mass of an atom of an element, expressed in atomic mass units Atomic mass unit (amu): 1.661 x 10-24 g Atomic weight: Average mass of all isotopes of a given

### Calculations with Chemical Formulas and Equations

Chapter 3 Calculations with Chemical Formulas and Equations Concept Check 3.1 You have 1.5 moles of tricycles. a. How many moles of seats do you have? b. How many moles of tires do you have? c. How could

### 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

### 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

### Formulas, Equations and Moles

Chapter 3 Formulas, Equations and Moles Interpreting Chemical Equations You can interpret a balanced chemical equation in many ways. On a microscopic level, two molecules of H 2 react with one molecule

### Chemical Reactions. Chemistry 100. Bettelheim, Brown, Campbell & Farrell. Introduction to General, Organic and Biochemistry Chapter 4

Chemistry 100 Bettelheim, Brown, Campbell & Farrell Ninth Edition Introduction to General, Organic and Biochemistry Chapter 4 Chemical Reactions Chemical Reactions In a chemical reaction, one set of chemical

### 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

### Stoichiometry. 1. The total number of moles represented by 20 grams of calcium carbonate is (1) 1; (2) 2; (3) 0.1; (4) 0.2.

Stoichiometry 1 The total number of moles represented by 20 grams of calcium carbonate is (1) 1; (2) 2; (3) 01; (4) 02 2 A 44 gram sample of a hydrate was heated until the water of hydration was driven

### 11-1 Stoichiometry. Represents

11-1 Stoichiometry What is stoichiometry? Calculations that relate the quantities of substances. It is the study of quantitative (measurable amounts) relationships in chemical reactions and equations.

### Chapter 3 Calculation with Chemical Formulas and Equations

Chapter 3 Calculation with Chemical Formulas and Equations Practical Applications of Chemistry Determining chemical formula of a substance Predicting the amount of substances consumed during a reaction

### Chemistry Stoichiometry Lesson 8 Lesson Plan David V. Fansler

Chemistry Stoichiometry Lesson 8 Lesson Plan David V. Fansler The Arithmetic of Equations Objectives: Interpret balanced chemical equations in terms of interacting moles, representative particles, masses,

### Unit 9 Stoichiometry Notes (The Mole Continues)

Unit 9 Stoichiometry Notes (The Mole Continues) is a big word for a process that chemist s use to calculate amounts in reactions. It makes use of the coefficient ratio set up by balanced reaction equations

### Chem 115 POGIL Worksheet - Week 4 Moles & Stoichiometry

Chem 115 POGIL Worksheet - Week 4 Moles & Stoichiometry Why? Chemists are concerned with mass relationships in chemical reactions, usually run on a macroscopic scale (grams, kilograms, etc.). To deal with

### Chapter 12 Stoichiometry

Chapter 12 Stoichiometry I. How much can a reaction produce? (12.1) A. Proportional Relationships 1. like recipes 2. how much can I get? 3. how much do I need? Stoichiometry: mass and quantity relationships

### MOLE CONVERSION PROBLEMS. 2. How many moles are present in 34 grams of Cu(OH) 2? [0.35 moles]

MOLE CONVERSION PROBLEMS 1. What is the molar mass of MgO? [40.31 g/mol] 2. How many moles are present in 34 grams of Cu(OH) 2? [0.35 moles] 3. How many moles are present in 2.5 x 10 23 molecules of CH

### F321 MOLES. Example If 1 atom has a mass of 1.241 x 10-23 g 1 mole of atoms will have a mass of 1.241 x 10-23 g x 6.02 x 10 23 = 7.

Moles 1 MOLES The mole the standard unit of amount of a substance (mol) the number of particles in a mole is known as Avogadro s constant (N A ) Avogadro s constant has a value of 6.02 x 10 23 mol -1.

### Lecture Notes Chemistry E-1. Chapter 3

Lecture Notes Chemistry E-1 Chapter 3 http://inserbia.info/news/wp-content/uploads/2013/05/tamiflu.jpg http://nutsforhealthcare.files.wordpress.com/2013/01/tamiflu-moa.jpg The Mole A mole is a certain

### IB Chemistry 1 Mole. One atom of C-12 has a mass of 12 amu. One mole of C-12 has a mass of 12 g. Grams we can use more easily.

The Mole Atomic mass units and atoms are not convenient units to work with. The concept of the mole was invented. This was the number of atoms of carbon-12 that were needed to make 12 g of carbon. 1 mole

### 7-5.5. Translate chemical symbols and the chemical formulas of common substances to show the component parts of the substances including:

7-5.5 Translate chemical symbols and the chemical formulas of common substances to show the component parts of the substances including: NaCl [salt], H 2 O [water], C 6 H 12 O 6 [simple sugar], O 2 [oxygen

### THE MOLE / COUNTING IN CHEMISTRY

1 THE MOLE / COUNTING IN CHEMISTRY ***A mole is 6.0 x 10 items.*** 1 mole = 6.0 x 10 items 1 mole = 60, 00, 000, 000, 000, 000, 000, 000 items Analogy #1 1 dozen = 1 items 18 eggs = 1.5 dz. - to convert

### Honors Chemistry: Unit 6 Test Stoichiometry PRACTICE TEST ANSWER KEY Page 1. A chemical equation. (C-4.4)

Honors Chemistry: Unit 6 Test Stoichiometry PRACTICE TEST ANSWER KEY Page 1 1. 2. 3. 4. 5. 6. Question What is a symbolic representation of a chemical reaction? What 3 things (values) is a mole of a chemical

### 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.

### Atomic Masses. Chapter 3. Stoichiometry. Chemical Stoichiometry. Mass and Moles of a Substance. Average Atomic Mass

Atomic Masses Chapter 3 Stoichiometry 1 atomic mass unit (amu) = 1/12 of the mass of a 12 C atom so one 12 C atom has a mass of 12 amu (exact number). From mass spectrometry: 13 C/ 12 C = 1.0836129 amu

### Chapter Three: STOICHIOMETRY

p70 Chapter Three: STOICHIOMETRY Contents p76 Stoichiometry - The study of quantities of materials consumed and produced in chemical reactions. p70 3-1 Counting by Weighing 3-2 Atomic Masses p78 Mass Mass

### Chemical Reactions. Chemical Equations. Mole as Conversion Factor: To convert between number of particles and an equivalent number of moles:

Quantities of Reactants and Products CHAPTER 3 Chemical Reactions Stoichiometry Application of The Law of Conservation of Matter Chemical book-keeping Chemical Equations Chemical equations: Describe proportions

### 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

### Stoichiometry Exploring a Student-Friendly Method of Problem Solving

Stoichiometry Exploring a Student-Friendly Method of Problem Solving Stoichiometry comes in two forms: composition and reaction. If the relationship in question is between the quantities of each element

### Formulae, stoichiometry and the mole concept

3 Formulae, stoichiometry and the mole concept Content 3.1 Symbols, Formulae and Chemical equations 3.2 Concept of Relative Mass 3.3 Mole Concept and Stoichiometry Learning Outcomes Candidates should be

### Chapter 3 Mass Relationships in Chemical Reactions

Chapter 3 Mass Relationships in Chemical Reactions Student: 1. An atom of bromine has a mass about four times greater than that of an atom of neon. Which choice makes the correct comparison of the relative

### Chapter 1 The Atomic Nature of Matter

Chapter 1 The Atomic Nature of Matter 6. Substances that cannot be decomposed into two or more simpler substances by chemical means are called a. pure substances. b. compounds. c. molecules. d. elements.

### 10.3 Percent Composition and Chemical Formulas. Chapter 10 Chemical Quantities Percent Composition and Chemical Formulas

Chapter 10 Chemical Quantities 101 The Mole: A Measurement of Matter 102 Mole-Mass and Mole-Volume Relationships 103 Percent Composition and Chemical Formulas 1 CHEMISTRY & YOU What does the percent composition

### Chapter 3! Stoichiometry: Calculations with Chemical Formulas and Equations. Stoichiometry

Chapter 3! : Calculations with Chemical Formulas and Equations Anatomy of a Chemical Equation CH 4 (g) + 2O 2 (g) CO 2 (g) + 2 H 2 O (g) Anatomy of a Chemical Equation CH 4 (g) + 2 O 2 (g) CO 2 (g) + 2

### 0.786 mol carbon dioxide to grams g lithium carbonate to mol

1 2 Convert: 2.54 x 10 22 atoms of Cr to mol 4.32 mol NaCl to grams 0.786 mol carbon dioxide to grams 2.67 g lithium carbonate to mol 1.000 atom of C 12 to grams 3 Convert: 2.54 x 10 22 atoms of Cr to

### 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

### Module 5: Combustion Technology. Lecture 33: Combustion air calculation

1 P age Module 5: Combustion Technology Lecture 33: Combustion air calculation 2 P age Keywords: Heat of combustion, stoichiometric air, excess air, natural gas combustion Combustion air calculation The

### Stoichiometry. Unit Outline

3 Stoichiometry Unit Outline 3.1 The Mole and Molar Mass 3.2 Stoichiometry and Compound Formulas 3.3 Stoichiometry and Chemical Reactions 3.4 Stoichiometry and Limiting Reactants 3.5 Chemical Analysis

### Unit 3 Notepack Chapter 7 Chemical Quantities Qualifier for Test

Unit 3 Notepack Chapter 7 Chemical Quantities Qualifier for Test NAME Section 7.1 The Mole: A Measurement of Matter A. What is a mole? 1. Chemistry is a quantitative science. What does this term mean?

### Chemical Calculations: The Mole Concept and Chemical Formulas. AW Atomic weight (mass of the atom of an element) was determined by relative weights.

1 Introduction to Chemistry Atomic Weights (Definitions) Chemical Calculations: The Mole Concept and Chemical Formulas AW Atomic weight (mass of the atom of an element) was determined by relative weights.

### 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

### Stoichiometry. 1. The total number of moles represented by 20 grams of calcium carbonate is (1) 1; (2) 2; (3) 0.1; (4) 0.2.

Stoichiometry 1 The total number of moles represented by 20 grams of calcium carbonate is (1) 1; (2) 2; (3) 01; (4) 02 2 A 44 gram sample of a hydrate was heated until the water of hydration was driven

### Concept 1. The meaning and usefulness of the mole. The mole (or mol) represents a certain number of objects.

Chapter 3. Stoichiometry: Mole-Mass Relationships in Chemical Reactions Concept 1. The meaning and usefulness of the mole The mole (or mol) represents a certain number of objects. SI def.: the amount of

### DETERMINING THE ENTHALPY OF FORMATION OF CaCO 3

DETERMINING THE ENTHALPY OF FORMATION OF CaCO 3 Standard Enthalpy Change Standard Enthalpy Change for a reaction, symbolized as H 0 298, is defined as The enthalpy change when the molar quantities of reactants

### Chapter 5, Calculations and the Chemical Equation

1. How many iron atoms are present in one mole of iron? Ans. 6.02 1023 atoms 2. How many grams of sulfur are found in 0.150 mol of sulfur? [Use atomic weight: S, 32.06 amu] Ans. 4.81 g 3. How many moles

### K c = [C]c [D] d [A] a [B] b. k f [NO 2 ] = k r [N 2 O 4 ] = K eq = The Concept of Equilibrium. Chapter 15 Chemical Equilibrium

Chapter 15 Chemical Equilibrium Learning goals and key skills: Understand what is meant by chemical equilibrium and how it relates to reaction rates Write the equilibrium-constant expression for any reaction

### 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

### Chemical Calculations: Formula Masses, Moles, and Chemical Equations

Chemical Calculations: Formula Masses, Moles, and Chemical Equations Atomic Mass & Formula Mass Recall from Chapter Three that the average mass of an atom of a given element can be found on the periodic

### stoichiometry = the numerical relationships between chemical amounts in a reaction.

1 REACTIONS AND YIELD ANSWERS stoichiometry = the numerical relationships between chemical amounts in a reaction. 2C 8 H 18 (l) + 25O 2 16CO 2 (g) + 18H 2 O(g) From the equation, 16 moles of CO 2 (a greenhouse

### CHEMICAL REACTIONS. Chemistry 51 Chapter 6

CHEMICAL REACTIONS A chemical reaction is a rearrangement of atoms in which some of the original bonds are broken and new bonds are formed to give different chemical structures. In a chemical reaction,

### Appendix D. Reaction Stoichiometry D.1 INTRODUCTION

Appendix D Reaction Stoichiometry D.1 INTRODUCTION In Appendix A, the stoichiometry of elements and compounds was presented. There, the relationships among grams, moles and number of atoms and molecules