# Example Problems. PV nt =R so P i. V i n i T i. = P f V f n f T f. (since V and n are constant) = P f T f. T i

Save this PDF as:

Size: px
Start display at page:

Download "Example Problems. PV nt =R so P i. V i n i T i. = P f V f n f T f. (since V and n are constant) = P f T f. T i"

## Transcription

1 The temperature of 2.5 L of a gas initially at STP is raised to 250 o C at constant volume. Calculate the final pressure of the gas in atm. PV nt =R so P i V i n i T i = P f V f n f T f or P i T i = P f T f (since V and n are constant)

2 The temperature of 2.5 L of a gas initially at STP is raised to 250 o C at constant volume. Calculate the final pressure of the gas in atm. P f = P i T f T i = 1atm 523 K 298 K = 1.75atm

3 At STP, L of a gas weighs 0.400g. Calculate the molar mass of the gas. M= mrt PV = 0.400g Latm/molK 298 K 1 atm 0.280l =35.0 g/mol

4 A compound has the empirical formula SF 4. At 20 o C, 0.100g of the gaseous compound occupies a volume of 22.1 ml and exerts a pressure of 1.02 atm. What is the molecular formula of the compound? Empirical formula mass = g/mol M = mrt/pv = x x 293/ 1.02 x = 107 g/mol ratio molar mass to empirical formula mass: 107 : 108 1:1 molecular formula: SF 4

5 Methane, the principal component of natural gas, is used for heating and cooking. The combustion process is: CH 4 + 2O 2 CO 2 + 2H 2 O If 15.0 moles of CH 4 are reacted what is the volume of CO 2 in liters produced at 23.0 o C and atm? Mols CO 2 produced = 15.0 mol CH 4 x 1 mol CO 2 /1 mol CH 4 = 15.0 mols V = nrt/p = 15.0 mol x latm/molk x 296 K/ atm = 370 L

6 A piece of sodium metal reacts completely with water as follows: 2Na + 2H 2 O 2NaOH + H 2 The H 2 gas is collected over water at 25.0 o C. The volume of the gas is 246 ml measured at 1.00 atm. Calculate the number of grams of Na used in the reaction (Vapor pressure of water at 25 o C = atm). P T = P H2 + P H2O P H2 = P T - P H2O = = 0.97 atm

7 A piece of sodium metal reacts completely with water as follows: 2Na + 2H 2 O 2NaOH + H 2 The H 2 gas is collected over water at 25.0 o C. The volume of the gas is 246 ml measured at 1.00 atm. Calculate the number of grams of Na used in the reaction (Vapor pressure of water at 25 o C = atm). n H2 = PV/RT = 0.97 atm x L / Latm/molK x 298 K = mol mols Na = mol H 2 x 2 mol Na/ 1 mol H 2 = mol mass Na = mol x g/mol = 0.45g

8 A mixture of Ar and N 2 gases has a density of g/l at STP. What is the mole fraction of the gas? Recalling the equation M = drt/p that can be used to calculate a molar mass from a density: M = g/l x Latm/molK x 298 K / 1 atm = 34.6 g/mol This is intermediate between the molar masses of N 2, g/mol, and Ar, g/mol and is the weighted average of the two... in exactly the same way that the average atomic mass is the weighted average of isotopes.

9 A mixture of Ar and N 2 gases has a density of g/l at STP. What is the mole fraction of the gas? 34.6 = X N2 x (1-X N2 ) x X N2 = ( )/( ) = therefore, X Ar = = 0.55

10 A 36.4 L volume of methane gas is heated from 25 o C to 88 o C at constant pressure. What is the final volume of the gas? P f = P i T f T i = 1atm 523 K 298 K =1.75atm

11 Iodine, I 2, reacts with aqueous thiosulfate ion in neutral solution according to the equation: I 2 + S 2 O 3 2- S 4 O I - How many grams of I 2 are present in a solution if ml of M Na 2 S 2 O 3 solution is needed to titrate the I 2 solution? Balance the equation: 1. I 2 + 2e - 2I - 2S 2 O 3 2- S 4 O e - 2. I 2 + 2S 2 O 3 2- S 4 O I -

12 Iodine, I 2, reacts with aqueous thiosulfate ion in neutral solution according to the equation: I 2 + 2S 2 O 3 2- S 4 O I - How many grams of I 2 are present in a solution if ml of M Na 2 S 2 O 3 solution is needed to titrate the I 2 solution? Mols Na 2 S 2 O 3 = L x mol/l = mol mols I 2 = mols Na 2 S 2 O 3 x 1 mol I 2 / 2 mols Na 2 S 2 O 3 = mol mass I 2 = mol x g/mol = g

13 Iron in a sample can be determined by titrating with cerium ion: Fe 2+ + Ce 4+ Fe 3+ + Ce 3+ What is the mass percentage of iron in a sample if titration of g of the sample requires ml of M Ce 4+? Mols Ce 4+ = L x mol/l = mol mols Fe 2+ = mol Ce 4+ x 1 mol Fe 2+ /1 mol Ce 4+ = mol mass Fe = mol x g/mol = g mass %Fe = (0.3292g/1.2284g) x 100 = 26.80%

14 If 1.87 g of acetic acid, C 2 H 4 O 2, reacts with 2.31 g of isopentyl alcohol, C 5 H 12 O to give 2.96 g of isopentyl acetate, C 7 H 14 O 2, what is the percent yield? Balanced equation: C 2 H 4 O 2 + C 5 H 12 O C 7 H 14 O 2 + H 2 O limiting reagent approach 1. mols acetic acid = 1.87 g / g/mol = mol mols C 7 H 14 O 2 = mol 2. mols C 5 H 12 O = 2.31 g / g/mol = mol mols C 7 H 14 O 2 = mol So, C 5 H 12 O is the limiting reagent.

15 If 1.87 g of acetic acid, C 2 H 4 O 2, reacts with 2.31 g of isopentyl alcohol, C 5 H 12 O to give 2.96 g of isopentyl acetate, C 7 H 14 O 2, what is the percent yield? Mass C 7 H 14 O 2 = mol x g/mol = 3.41 g (theoretical yield) Percent yield = (actual yield/theoretical yield) x 100 = (2.96/3.41) x 100 = 78.9%

16 An average cup of coffee contains about 125 mg of caffeine, C 8 H 10 N 4 O 2. How many moles of caffeine are in a cup? How many molecules of caffeine? Mols caffeine = 125 mg x (1 g/1000 mg) / g/mol = 6.44 x 10-4 mol Molecules caffeine = 6.44 x 10-4 mol x x molecule/mol = 3.88 x molecules

17 A g sample of a metal carbonate MCO 3 was reacted with ml of M H 2 SO 4 yielding CO 2 gas and an aqueous solution of the metal sulfate. The CO 2 was removed by boiling and the remaining H 2 SO 4 was titrated with M NaOH, requiring ml to reach the endpoint. What is the metal? 2NaOH + H 2 SO 4 Na 2 SO 4 + 2H 2 O starting mols H 2 SO 4 = L x mol/l = mol mols H 2 SO 4 left = mols NaOH x 1 mol H 2 SO 4 / 2 mol NaOH = L x mol/l x ½ = mol mols H 2 SO 4 used = = mol

18 A g sample of a metal carbonate MCO 3 was reacted with ml of M H 2 SO 4 yielding CO 2 gas and an aqueous solution of the metal sulfate. The CO 2 was removed by boiling and the remaining H 2 SO 4 was titrated with M NaOH, requiring ml to reach the endpoint. What is the metal? MCO 3 + H 2 SO 4 MSO 4 + H 2 O mols H 2 SO 4 used = mols MCO 3 = mol molar mass MCO 3 = g/ mol = g/mol mass M in 1 mol = mass MCO 3 mass CO 3 = = g/mol Barium

19 The fictional isotope Xium-60 has an atomic mass of units while Xium 70 has an atomic mass of units. The average mass of Xium is units. What is the fractional abundance of Xium 70? Average atomic mass = fraction A x atomic mass A + fraction B x atomic mass B amu = fraction 60 x amu + fraction 70 x = (1 - fraction 70) x fraction 70 x fraction 70 =

20 Calculate the number of neutrons in an atom of 239 Pu. Atomic number of plutonium = 94 mass number = 239 = number of neutrons + number of protons number of neutrons = mass number number of protons = = 145

21 Permanganate, MnO 4 -, reacts with nitrite, NO 2 -, to produce manganese (IV) oxide and nitrate. Balance the equation. 1. half reactions: MnO e - MnO 2 NO 2 - NO e - 2. balance oxygens: MnO e - MnO 2 + 2H 2 O NO H 2 O NO e - 3. balance hydrogens: MnO H + + 3e - MnO 2 + 2H 2 O NO H 2 O NO H + + 2e -

22 Permanganate, MnO 4 -, reacts with nitrite, NO 2 -, to produce manganese (IV) oxide and nitrate. Balance the equation. 4. add half reactions: 2MnO H + + 6e - 2MnO 2 + 4H 2 O 3NO H 2 O 3NO H + + 6e - 2MnO H + + 3NO 2-2MnO 2 + 3NO H 2 O 5. adjust for basic solution if necessary: 2MnO H + + 2OH - + 3NO 2-2MnO 2 + 3NO H 2 O + 2OH - 2MnO H 2 O + 3NO 2-2MnO 2 + 3NO OH -

23 Acetylsalicylic acid (C 9 H 8 O 4 ) commonly known as "aspirin" is an acid that can ionize to produce one H + ion. A typical aspirin tablet, however, contains only a small amount of the acid. In an experiment to determine its composition, an aspirin tablet was crushed and dissolved in water. It took ml of M NaOH to neutralize the solution. Calculate the number of grams of aspirin in the tablet. HA + NaOH NaA + H 2 O mols NaOH = L x mol/l = mol mols HA = mols NaOH x 1 mol HA / 1 mol NaOH = mol mass HA = mol x g/mol = g

24 Titration with solutions of potassium bromate, KBrO 3, can be used to determine the concentration of As(III). What is the molar concentration of As(III) in a solution if ml of M KBrO3 is needed to titrate ml of the As(III) solution? The (unbalanced) equation is: H 3 AsO 3 + BrO 3 - Br - + H 3 AsO 4 1. half reactions: H 3 AsO 3 H 3 AsO 4 + 2e - BrO e - Br - 2. balance oxygens: H 3 AsO 3 + H 2 O H 3 AsO 4 + 2e - BrO e - Br - + 3H 2 O

25 Titration with solutions of potassium bromate, KBrO 3, can be used to determine the concentration of As(III). What is the molar concentration of As(III) in a solution if ml of M KBrO3 is needed to titrate ml of the As(III) solution? The (unbalanced) equation is: H 3 AsO 3 + BrO 3 - Br - + H 3 AsO 4 3. balance hydrogens: H 3 AsO 3 + H 2 O H 3 AsO 4 + 2H + + 2e - BrO H + + 6e - Br - + 3H 2 O 4. add half reactions: 3H 3 AsO 3 + 3H 2 O 3H 3 AsO 4 + 6H + + 6e - BrO H + + 6e - Br - + 3H 2 O 3H 3 AsO 3 + BrO 3-3H 3 AsO 4 + Br -

26 Titration with solutions of potassium bromate, KBrO 3, can be used to determine the concentration of As(III). What is the molar concentration of As(III) in a solution if ml of M KBrO3 is needed to titrate ml of the As(III) solution? The (unbalanced) equation is: H 3 AsO 3 + BrO 3 - Br - + H 3 AsO 4 Mols BrO 3 - = L x mol/l = mol mols H 3 AsO 3 = mols BrO 3 - x 3 mol H 3 AsO 3 / 1 mol BrO 3 - = mol [H 3 AsO 3 ] = mol / L = mol/l

### 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.

### 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

### 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 +

### neutrons are present?

AP Chem Summer Assignment Worksheet #1 Atomic Structure 1. a) For the ion 39 K +, state how many electrons, how many protons, and how many 19 neutrons are present? b) Which of these particles has the smallest

### 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

### 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,

### 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

### 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

### 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

### 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?

### Calculation of Molar Masses. Molar Mass. Solutions. Solutions

Molar Mass Molar mass = Mass in grams of one mole of any element, numerically equal to its atomic weight Molar mass of molecules can be determined from the chemical formula and molar masses of elements

### Useful only for measuring the mass of very small objects atoms and molecules!

Chapter 9 Chemical Composition (Moles) Which weighs more, 1 atom of He or 1 atom of O? Units of mass: Pound Kilogram Atomic mass unit (AMU) There are others! 1 amu = 1.66 x 10-24 grams = mass of a proton

### The Mole. Chapter 10. Dimensional Analysis. The Mole. How much mass is in one atom of carbon-12? Molar Mass of Atoms 3/1/2015

The Mole Chapter 10 1 Objectives Use the mole and molar mass to make conversions among moles, mass, and number of particles Determine the percent composition of the components of a compound Calculate empirical

### 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

### 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

### Mole Notes.notebook. October 29, 2014

1 2 How do chemists count atoms/formula units/molecules? How do we go from the atomic scale to the scale of everyday measurements (macroscopic scale)? The gateway is the mole! But before we get to the

### Solution. Practice Exercise. Concept Exercise

Example Exercise 9.1 Atomic Mass and Avogadro s Number Refer to the atomic masses in the periodic table inside the front cover of this textbook. State the mass of Avogadro s number of atoms for each of

### 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

### 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

### 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

### Unit 7A - The Mole. We Need to Count atoms. The Mole and Molar Mass

Unit 7A - The Mole The Mole and Molar Mass We Need to Count atoms Airbags are inflated by a chemical reaction: electrical 2 NaN 3 (s) 3 N 2 (g) + 2 Na(s) decomposition Each airbag needs the right amount

### 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

### 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 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.

### Multiple Choice questions (one answer correct)

Mole Concept Multiple Choice questions (one answer correct) (1) Avogadro s number represents the number of atoms in (a) 12g of C 12 (b) 320g of sulphur (c) 32g of oxygen (d) 12.7g of iodine (2) The number

### Chapter 4. Chemical Composition. Chapter 4 Topics H 2 S. 4.1 Mole Quantities. The Mole Scale. Molar Mass The Mass of 1 Mole

Chapter 4 Chemical Composition Chapter 4 Topics 1. Mole Quantities 2. Moles, Masses, and Particles 3. Determining Empirical Formulas 4. Chemical Composition of Solutions Copyright The McGraw-Hill Companies,

### CHAPTER 8: CHEMICAL COMPOSITION

CHAPTER 8: CHEMICAL COMPOSITION Active Learning: 1-4, 6-8, 12, 18-25; End-of-Chapter Problems: 3-4, 9-82, 84-85, 87-92, 94-104, 107-109, 111, 113, 119, 125-126 8.2 ATOMIC MASSES: COUNTING ATOMS BY WEIGHING

### 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

### HOMEWORK 4A. Definitions. Oxidation-Reduction Reactions. Questions

HOMEWORK 4A Oxidation-Reduction Reactions 1. Indicate whether a reaction will occur or not in each of following. Wtiring a balcnced equation is not necessary. (a) Magnesium metal is added to hydrochloric

### 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

### Liquid phase. Balance equation Moles A Stoic. coefficient. Aqueous phase

STOICHIOMETRY Objective The purpose of this exercise is to give you some practice on some Stoichiometry calculations. Discussion The molecular mass of a compound is the sum of the atomic masses of all

### Element of same atomic number, but different atomic mass o Example: Hydrogen

Atomic mass: p + = protons; e - = electrons; n 0 = neutrons p + + n 0 = atomic mass o For carbon-12, 6p + + 6n 0 = atomic mass of 12.0 o For chlorine-35, 17p + + 18n 0 = atomic mass of 35.0 atomic mass

### 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

### 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

### Chemistry 65 Chapter 6 THE MOLE CONCEPT

THE MOLE CONCEPT Chemists find it more convenient to use mass relationships in the laboratory, while chemical reactions depend on the number of atoms present. In order to relate the mass and number of

### W1 WORKSHOP ON STOICHIOMETRY

INTRODUCTION W1 WORKSHOP ON STOICHIOMETRY These notes and exercises are designed to introduce you to the basic concepts required to understand a chemical formula or equation. Relative atomic masses of

### 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

### Study Guide For Chapter 7

Name: Class: Date: ID: A Study Guide For Chapter 7 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. The number of atoms in a mole of any pure substance

### Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.

Introduction to Chemistry Exam 2 Practice Problems 1 Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1.Atoms consist principally of what three

### 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

### 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

### The Mole Concept. A. Atomic Masses and Avogadro s Hypothesis

The Mole Concept A. Atomic Masses and Avogadro s Hypothesis 1. We have learned that compounds are made up of two or more different elements and that elements are composed of atoms. Therefore, compounds

### 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

### PART I: MULTIPLE CHOICE (30 multiple choice questions. Each multiple choice question is worth 2 points)

CHEMISTRY 123-07 Midterm #1 Answer key October 14, 2010 Statistics: Average: 74 p (74%); Highest: 97 p (95%); Lowest: 33 p (33%) Number of students performing at or above average: 67 (57%) Number of students

### 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

### 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

### From the book (10, 12, 16, 18, 22, 24 52, 54, 56, 58, 62, 64, 66, 68, 74, 76, 78, 80, 82, 86, 88, 90, 92, 106 and 116)

Chem 112 Solutions From the book (10, 12, 16, 18, 22, 24 52, 54, 56, 58, 62, 64, 66, 68, 74, 76, 78, 80, 82, 86, 88, 90, 92, 106 and 116) 1. Which of the following compounds are nonelectrolytes? A. NaF

### 2. ATOMIC, MOLECULAR AND EQUIVALENT MASSES

2. ATOMIC, MOLECULAR AND EQUIVALENT MASSES INTRODUCTION: EQUIVALENT WEIGHT Since hydrogen is the lightest of all elements, it was chosen as a standard for determination of equivalent weights. On this basis,

### 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.

### Solution a homogeneous mixture = A solvent + solute(s) Aqueous solution water is the solvent

Solution a homogeneous mixture = A solvent + solute(s) Aqueous solution water is the solvent Water a polar solvent: dissolves most ionic compounds as well as many molecular compounds Aqueous solution:

### CHAPTER 3 COMPOUNDS AND MOLECULES

Chapter 3 Compounds and Molecules Page 1 CHAPTER 3 COMPOUNDS AND MOLECULES 3-1. Octane, a component of gasoline, has eight carbon atoms and eighteen hydrogen atoms per molecule. Its formula is written

### 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?

### Atomic mass is the mass of an atom in atomic mass units (amu)

Micro World atoms & molecules Laboratory scale measurements Atomic mass is the mass of an atom in atomic mass units (amu) By definition: 1 atom 12 C weighs 12 amu On this scale 1 H = 1.008 amu 16 O = 16.00

### 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 6 Oxidation-Reduction Reactions. Section 6.1 2. Which one of the statements below is true concerning an oxidation-reduction reaction?

Chapter 6 Oxidation-Reduction Reactions 1. Oxidation is defined as a. gain of a proton b. loss of a proton c. gain of an electron! d. loss of an electron e. capture of an electron by a neutron 2. Which

### Name Date Class CHEMICAL QUANTITIES. SECTION 10.1 THE MOLE: A MEASUREMENT OF MATTER (pages 287 296)

Name Date Class 10 CHEMICAL QUANTITIES SECTION 10.1 THE MOLE: A MEASUREMENT OF MATTER (pages 287 296) This section defines the mole and explains how the mole is used to measure matter. It also teaches

### 1. When the following equation is balanced, the coefficient of Al is. Al (s) + H 2 O (l)? Al(OH) 3 (s) + H 2 (g)

1. When the following equation is balanced, the coefficient of Al is. Al (s) + H 2 O (l)? Al(OH) (s) + H 2 (g) A) 1 B) 2 C) 4 D) 5 E) Al (s) + H 2 O (l)? Al(OH) (s) + H 2 (g) Al (s) + H 2 O (l)? Al(OH)

### 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

### 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

### 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

### 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

### 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

### 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

### midterm1, 2009 Name: Class: Date:

Class: Date: midterm1, 2009 Record your name on the top of this exam and on the scantron form. Record the test ID letter in the top right box of the scantron form. Record all of your answers on the scantron

### 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

### Chapter 4 Notes - Types of Chemical Reactions and Solution Chemistry

AP Chemistry A. Allan Chapter 4 Notes - Types of Chemical Reactions and Solution Chemistry 4.1 Water, the Common Solvent A. Structure of water 1. Oxygen's electronegativity is high (3.5) and hydrogen's

### Name Date Class CHEMICAL QUANTITIES. SECTION 10.1 THE MOLE: A MEASUREMENT OF MATTER (pages 287 296)

10 CHEMICAL QUANTITIES SECTION 10.1 THE MOLE: A MEASUREMENT OF MATTER (pages 287 296) This section defines the mole and explains how the mole is used to measure matter. It also teaches you how to calculate

### 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.

### 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

### Reactions. Balancing Chemical Equations uses Law of conservation of mass: matter cannot be lost in any chemical reaction

Reactions Chapter 8 Combustion Decomposition Combination Chapter 9 Aqueous Reactions Exchange reactions (Metathesis) Formation of a precipitate Formation of a gas Formation of a week or nonelectrolyte

### 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 1: Moles and equations. Learning outcomes. you should be able to:

Chapter 1: Moles and equations 1 Learning outcomes you should be able to: define and use the terms: relative atomic mass, isotopic mass and formula mass based on the 12 C scale perform calculations, including

### 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)

### Chemistry I Exam 1 review

Chemistry I Exam 1 review Name: For the multiple choice problems, mark the correct answer on the scantron with the corresponding problem number. For the open ended problems, show your work on the test,

### 2008 SOL Test. Name: Score: 50 / 50 points (100%)

Name: Score: 50 / 50 points (100%) 2008 SOL Test Multiple Choice Identify the choice that best completes the statement or answers the question. C 1. Trial Concentration 1 0.971 M 2 0.982 M 3 1.02 M 4 0.971

### Tutorial 4 SOLUTION STOICHIOMETRY. Solution stoichiometry calculations involve chemical reactions taking place in solution.

T-27 Tutorial 4 SOLUTION STOICHIOMETRY Solution stoichiometry calculations involve chemical reactions taking place in solution. Of the various methods of expressing solution concentration the most convenient

### 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

### 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

### Moles. Moles. Moles. Moles. Balancing Eqns. Balancing. Balancing Eqns. Symbols Yields or Produces. Like a recipe:

Like a recipe: Balancing Eqns Reactants Products 2H 2 (g) + O 2 (g) 2H 2 O(l) coefficients subscripts Balancing Eqns Balancing Symbols (s) (l) (aq) (g) or Yields or Produces solid liquid (pure liquid)

### Unit 6 The Mole Concept

Chemistry Form 3 Page 62 Ms. R. Buttigieg Unit 6 The Mole Concept See Chemistry for You Chapter 28 pg. 352-363 See GCSE Chemistry Chapter 5 pg. 70-79 6.1 Relative atomic mass. The relative atomic mass

### Colligative Properties

CH302 LaBrake and Vanden Bout Colligative Properties PROBLEM #1: Give the molecular formula, the van t hoff factor for the following Ionic Compounds as well as guess the solubility of the compounds. If

### Problems you need to KNOW to be successful in the upcoming AP Chemistry exam.

Problems you need to KNOW to be successful in the upcoming AP Chemistry exam. Problem 1 The formula and the molecular weight of an unknown hydrocarbon compound are to be determined by elemental analysis

### 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

### 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

### MOLES AND MOLE CALCULATIONS

35 MOLES ND MOLE CLCULTIONS INTRODUCTION The purpose of this section is to present some methods for calculating both how much of each reactant is used in a chemical reaction, and how much of each product

### 1 What is the angular momentum quantum number (l) value for the 3p sublevel? A 1

1 What is the angular momentum quantum number (l) value for the 3p sublevel? 1 2 3 4 ORRET: For the 3p sublevel, the principal quantum number (n) is 3 and the angular momentum quantum number (l) is 1.

### CHEMISTRY II FINAL EXAM REVIEW

Name Period CHEMISTRY II FINAL EXAM REVIEW Final Exam: approximately 75 multiple choice questions Ch 12: Stoichiometry Ch 5 & 6: Electron Configurations & Periodic Properties Ch 7 & 8: Bonding Ch 14: Gas

### CP Chemistry Review for Stoichiometry Test

CP Chemistry Review for Stoichiometry Test Stoichiometry Problems (one given reactant): 1. Make sure you have a balanced chemical equation 2. Convert to moles of the known substance. (Use the periodic

### Name: Regents Chemistry Review Packet A

Name: Regents Chemistry Review Packet A 1. According to the modern model of the atom, the nucleus of an atom is surrounded by one or more A) electrons B) neutrons A) an alpha particle B) a beta particle

### MOLAR MASS AND MOLECULAR WEIGHT Themolar mass of a molecule is the sum of the atomic weights of all atoms in the molecule. Molar Mass.

Counting Atoms Mg burns in air (O 2 ) to produce white magnesium oxide, MgO. How can we figure out how much oxide is produced from a given mass of Mg? PROBLEM: If If 0.200 g of Mg is is burned, how much

### 602X10 21 602,000,000,000, 000,000,000,000 6.02X10 23. Pre- AP Chemistry Chemical Quan44es: The Mole. Diatomic Elements

Pre- AP Chemistry Chemical Quan44es: The Mole Mole SI unit of measurement that measures the amount of substance. A substance exists as representa9ve par9cles. Representa9ve par9cles can be atoms, molecules,

### Mole Concept and Stoichiometry

1 Mole Concept and Stoichiometry Concept Mole Concept Introduction This is our common experience that when we go to market to buy something, a few things we always get in definite numbers. For example,

### 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

### APPENDIX B: EXERCISES

BUILDING CHEMISTRY LABORATORY SESSIONS APPENDIX B: EXERCISES Molecular mass, the mole, and mass percent Relative atomic and molecular mass Relative atomic mass (A r ) is a constant that expresses the ratio

### 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

### 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

### MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

Chapter 10 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A gas at a pressure of 10.0 Pa exerts a force of N on an area of 5.5 m2. A) 1.8 B) 0.55