# The Mole Concept. The Mole. Masses of molecules

 To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video
Save this PDF as:

Size: px
Start display at page:

## Transcription

1 The Mole Concept Ron Robertson r2 c:\files\courses\ \2010 final slides for web\mole concept.docx The Mole The mole is a unit of measurement equal to x things (to 4 sf) just like there are 12 things in a dozen. This number is called Avogadro s number. Why x 10 23? Let s look at a couple of calculations. If the molecular weight (MW) of water is amu, how many molecules are in g? If the atomic weight (AW) of sodium is amu, how many atoms are in g? The Mole Concept Slide 2 Masses of molecules We can take the masses of individual atoms and add them together to obtain the mass of a molecule or formula unit. : H 2 O amu Terms Average mass per atom Atomic weight Average mass per molecule Molecular weight, Molecular mass, Formula weight, Formula mass Thus the mole is the number of things that makes the numerical value of the mass per atom or molecule in units of amu equal to the mass in grams. The actual definition states it a little differently the mole is the amount of substance that contains as many particles (atoms, molecules, formula units, ions, etc.) as there are atoms in exactly 12 g of the carbon-12 isotope. Our choice of the amu as 1/12 of the mass of a carbon-12 atom makes the number of atoms x The Mole Concept Slide 1 The Mole Concept Slide 3

2 This gives us 2 new conversion factors! How many grams of water does it take to contain 50.0 g of hydrogen? 1 mole = x particles 1 mole =? g (The Molar Mass) The number of grams has the same numerical value as the mass per atom or the mass per molecule. s: 89 g of sodium = atoms How many grams of oxygen are in a mole of water? 1.50 moles of Na = g Na x atoms of Na = moles of Na The Mole Concept Slide 4 The Mole Concept Slide 6 Percentage Composition by Mass 1. Since a substance is composed of identical repeating units (formula units or molecules), the relative proportions of a unit are the same as the whole substance What is the percentage composition of water? 2. This percentage has a meaning that can be applied many ways percentage per molecule % per group of molecules Empirical formula The simplest ratio of atoms in a molecule of a compound This can be found from the percentage composition or any composition data. Why? Since a mole of any element contains the same number of atoms, a ratio of moles will be the same as a ratio of atoms. The Mole Concept Slide 5 The Mole Concept Slide 7

3 To find the empirical formula 1. Find the number of moles of each element in the sample 2. Determine the simplest whole number ratio between them, this is the empirical formula. If the ratio at first does not give whole numbers, multiply each ratio factor by the smallest whole number that would convert all the numbers to integers. Hydrates Hydrates are solid ionic compounds with water molecules attached in a specific ratio; an ionic crystal with water trapped on the inside in a specific ratio To obtain the formula find the number of moles of ionic compound and the number of moles of water Then determine the ratio; the ratio of moles will be the same as a ratio of molecules The Mole Concept Slide 8 The Mole Concept Slide 10 Molecular Formula The molecular formula is a multiple of the empirical formula To obtain the molecular formula find how many empirical formula units are contained in 1 molecule We need the following information 1. Empirical formula 2. Molecular Weight / Molar Mass After finding the number of empirical formula units per molecule multiply each subscript in the empirical formula by this factor Equations and Chemical Reactions A chemical equation summarizes a chemical process (chemical change or physical change) Reactants Products Equations use chemical symbols and must be balanced to give quantitative info. Balancing based on Law of Conservation of Matter The phases of each substance are often indicated with g, l, s, aq Balancing uses coefficients to make sure number of atoms of each element on reactant side = number of atoms of each element on the product side The Mole Concept Slide 9 The Mole Concept Slide 11

4 Stoichiometry Definition: The study of the quantitative relationships between reactants and products in a chemical reaction The balanced equation gives a ratio of moles between reactants and products since a ratio of molecules is the same as a ratio of moles. How much water can be produced from the reaction of 4.0 g of hydrogen gas with an excess of oxygen gas? Limiting reactants What if we are given two quantities of substance? Work the problem twice! Choose the smaller answer as the actual amount required or produced. Whatever you start with to obtain this smaller answer is the limiting reactant. How much water is produced if we react 4.00 g of hydrogen gas with 16.0 g of oxygen gas? The Mole Concept Slide 12 The Mole Concept Slide Write a balanced equation 2. Identify what you are given and what you need to solve for 3. Convert (if needed) what you are given to moles 4. Use stoichiometric ratios from balanced equation as a conversion from moles of what you have to what you want 5. Convert (if needed) to desired units How much oxygen gas is needed to react completely 4.0 g of hydrogen gas? (water is the product) Since we can only make 18.0 g of water from 16.0 g of oxygen, the amount of oxygen limits the production of water and is called the limiting reactant. What is present at the end of the reaction? Since we started with 4.00 g of hydrogen, 2.00 g are left. So g of water and 2.00 g of hydrogen are present at the end of the reaction. Notice that the law of conservation of matter holds! The Mole Concept Slide 13 The Mole Concept Slide 15

5 Percentage yield The numbers above are based on a perfect reaction. Suppose in the problem above that some of the water is lost in the measurement. We measure the relative amount actually obtained using the percentage yield. % yield = Actual yield Theoretical yield (100) What is the percentage yield in the previous example if 14.0 g of water are produced? The Mole Concept Slide 16

### Formulas, Equations, and Moles. + "reacts with" "to produce" Equations must be balanced. Equal amounts of each element on each side of the equation.

Chapter 3 Formulas, Equations, and Moles Chemical Equations 2 2 + 2 2 2 reactants products + "reacts with" "to produce" coefficients - indicate amount of substance Equations must be balanced. Equal amounts

### 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

### 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

### Chapter 3 Chemical Reactions and Reaction Stoichiometry. 許富銀 ( Hsu Fu-Yin)

Chapter 3 Chemical Reactions and Reaction Stoichiometry 許富銀 ( Hsu Fu-Yin) 1 Stoichiometry The study of the numerical relationship between chemical quantities in a chemical reaction is called stoichiometry.

### 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.

### 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

### The mass of the formula unit is called the formula mass Formula masses are calculated the same way as molecular masses

Chapter 4: The Mole Atomic mass provides a means to count atoms by measuring the mass of a sample The periodic table on the inside cover of the text gives atomic masses of the elements The mass of an atom

### Chemistry I: Using Chemical Formulas. Formula Mass The sum of the average atomic masses of all elements in the compound. Units are amu.

Chemistry I: Using Chemical Formulas Formula Mass The sum of the average atomic masses of all elements in the compound. Units are amu. Molar Mass - The mass in grams of 1 mole of a substance. Substance

### PERIODIC TABLE OF ELEMENTS. 4/23/14 Chapter 7: Chemical Reactions 1

PERIODIC TABLE OF ELEMENTS 4/23/14 Chapter 7: Chemical Reactions 1 CHAPTER 7: CHEMICAL REACTIONS 7.1 Describing Reactions 7.2 Types of Reactions 7.3 Energy Changes in Reactions 7.4 Reaction Rates 7.5 Equilibrium

### 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

### 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

### Stoichiometry Dr. M. E. Bridge

Preliminary Chemistry Course Stoichiometry Dr. M. E. Bridge What is stoichiometry? The meaning of the word: The word stoichiometry comes from two Greek words: (meaning element ) and (meaning measure )

### Chemical Composition. Introductory Chemistry: A Foundation FOURTH EDITION. Atomic Masses. Atomic Masses. Atomic Masses. Chapter 8

Introductory Chemistry: A Foundation FOURTH EDITION by Steven S. Zumdahl University of Illinois Chemical Composition Chapter 8 1 2 Atomic Masses Balanced equation tells us the relative numbers of molecules

### 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

### 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?

### AP Chemistry. Unit #3. Chapter 3 Zumdahl

AP Chemistry Unit #3 Chapter 3 Zumdahl Stoichiometry C6H12O6 + 6 O2 6 CO2 + 6 H2O Students should be able to: Calculate the atomic weight (average atomic mass) of an element from the relative abundances

### Chemical Equations and Calculations

Chemical Equations and Calculations A chemical equation is a shorthand way of indicating what is going on in a chemical reaction. We could do it the long way Two molecules of Hydrogen gas react with one

### 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

### 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

### We know from the information given that we have an equal mass of each compound, but no real numbers to plug in and find moles. So what can we do?

How do we figure this out? We know that: 1) the number of oxygen atoms can be found by using Avogadro s number, if we know the moles of oxygen atoms; 2) the number of moles of oxygen atoms can be found

### 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

### The Mole Concept and Atoms

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 4 24 September 2013 Calculations and the Chemical Equation The Mole Concept and Atoms Atoms are exceedingly

### MASS RELATIONS IN CHEMISTRY; STOICHIOMETRY

MASS RELATIONS IN CHEMISTRY; STOICHIOMETRY [MH5; Ch. 3] Each element has its own unique mass. The mass of each element is found on the Periodic Table under the chemical symbol for the element (it is usually

### 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

### Chapter 4 Chemical Equations & Stoichiometry

Chapter 4 Chemical Equations & Stoichiometry Chemical reactions are best described using equations which tells us what compounds we started with (reactants), what we did to them (reaction conditions) and

### Lecture 5, The Mole. What is a mole?

Lecture 5, The Mole What is a mole? Moles Atomic mass unit and the mole amu definition: 12 C = 12 amu. The atomic mass unit is defined this way. 1 amu = 1.6605 x 10-24 g How many 12 C atoms weigh 12 g?

### 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

### CHEMISTRY CP Name: KEY Period: UNIT 5: TEST REVIEW SHEET MOLE CONVERSIONS, EMPIRICAL/MOLECULAR FORMULA, STOICHIOMETRY

CHEMISTRY CP Name: KEY Period: UNIT 5: TEST REVIEW SHEET MOLE CONVERSIONS, EMPIRICAL/MOLECULAR FORMULA, STOICHIOMETRY MOLES AND MOLE CONVERSIONS 1. Things to Know: a. What is a mole? Avogadro s number

### CHEMICAL FORMULA COEFFICIENTS AND SUBSCRIPTS. Chapter 3: Molecular analysis 3O 2 2O 3

Chapter 3: Molecular analysis Read: BLB 3.3 3.5 H W : BLB 3:21a, c, e, f, 25, 29, 37,49, 51, 53 Supplemental 3:1 8 CHEMICAL FORMULA Formula that gives the TOTAL number of elements in a molecule or formula

### 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,

### 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

### = 16.00 amu. = 39.10 amu

Using Chemical Formulas Objective 1: Calculate the formula mass or molar mass of any given compound. The Formula Mass of any molecule, formula unit, or ion is the sum of the average atomic masses of all

### 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

### Chapter 3: ex. P2O5 molecular mass = 2(30.97 amu) + 5(16.00 amu) = amu

Molecular Mass and Formula Mass for molecular compounds: the molecular mass is the mass (in amu) of one molecule of the compound molecular mass = atomic masses of elements present Chapter 3: ex. P2O5 molecular

### 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

### 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 +

### 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

### CHEMISTRY. (i) It failed to explain how atoms of different elements differ from each other.

CHEMISTRY MOLE CONCEPT DALTON S ATOMIC THEORY By observing the laws of chemical combination, John Dalton proposed an atomic theory of matter. The main points of Dalton s atomic theory are as follows: (i)

### 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

### 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

### 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

### 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

### 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 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

### 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

### 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

### How much does a single atom weigh? Different elements weigh different amounts related to what makes them unique.

How much does a single atom weigh? Different elements weigh different amounts related to what makes them unique. What units do we use to define the weight of an atom? amu units of atomic weight. (atomic

### Chapter 3. Stoichiometry of Formulas and Equations

Chapter 3 Stoichiometry of Formulas and Equations Chapter 3 Outline: Mole - Mass Relationships in Chemical Systems 3.1 The Mole 3.2 Determining the Formula of an Unknown Compound 3.3 Writing and Balancing

### 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,

### 10 The Mole. Section 10.1 Measuring Matter

Name Date Class The Mole Section.1 Measuring Matter In your textbook, read about counting particles. In Column B, rank the quantities from Column A from smallest to largest. Column A Column B 0.5 mol 1.

### CHAPTER 3 Calculations with Chemical Formulas and Equations. atoms in a FORMULA UNIT

CHAPTER 3 Calculations with Chemical Formulas and Equations MOLECULAR WEIGHT (M. W.) Sum of the Atomic Weights of all atoms in a MOLECULE of a substance. FORMULA WEIGHT (F. W.) Sum of the atomic Weights

### If you remember, we left off this part of the story with defining the mass of one 12

Chapter 11 Chemical Calculations For the past several weeks we have been working on our qualitative understanding of first atoms, then molecules, and finally chemical reactions. In this chapter we enter

### Formula Stoichiometry. Text pages

Formula Stoichiometry Text pages 237-250 Formula Mass Review Write a chemical formula for the compound. H 2 CO 3 Look up the average atomic mass for each of the elements. H = 1.008 C= 12.01 O = 16.00 Multiply

### 7.1 Stoichiometry and Percent Yield

score /10 pts. Name Class Date 7.1 Stoichiometry and Percent Yield Mole Ratios An example: The combustion of propane is used to heat many rural homes in winter. Balance the equation below for the combustion

### Chapter 3. Mass Relationships in Chemical Reactions

Chapter 3 Mass Relationships in Chemical Reactions This chapter uses the concepts of conservation of mass to assist the student in gaining an understanding of chemical changes. Upon completion of Chapter

### Matter. Atomic weight, Molecular weight and Mole

Matter Atomic weight, Molecular weight and Mole Atomic Mass Unit Chemists of the nineteenth century realized that, in order to measure the mass of an atomic particle, it was useless to use the standard

### Simple vs. True. Simple vs. True. Calculating Empirical and Molecular Formulas

Calculating Empirical and Molecular Formulas Formula writing is a key component for success in chemistry. How do scientists really know what the true formula for a compound might be? In this lesson we

### 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

### 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

### AT Chapter 3 Notes 15.notebook. September 29, Measuring Atomic Masses

Measuring Atomic Masses Mass Spectrometer used to isolate isotopes of an element and determine their mass. 1 An element sample is heated to vaporize it and the gaseous atoms are zapped with an electron

### CHAPTER 11 - CHEMICAL QUANTITIES

I. THE MOLE CONCEPT CHAPTER 11 - CHEMICAL QUANTITIES A. What is a mole? 1. a mole is the SI unit of measurement of counting; just like a dozen is a measurement 2. a mole is a number a. 6.02 x 10 23 is

### 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.

### 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

### 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

### Practice questions for Ch. 3

Name: Class: Date: ID: A Practice questions for Ch. 3 1. A hypothetical element consists of two isotopes of masses 69.95 amu and 71.95 amu with abundances of 25.7% and 74.3%, respectively. What is the

### Stoichiometry. Types of Problems. Stoichiometry. Chemistry 1010 Review Tutorial 4/9/2013. Stoichiometry and Lewis Structures

Stoichiometry Chemistry 1010 Review Tutorial Stoichiometry and Lewis Structures April 9 th, 2013 Stoichiometry Stoichiometry involves MOLES Elements/compounds can only be compared side by side using moles

### Chemistry Stoichiometry. 45 points. Do not turn page until told to do so.

Chemistry 2010 Stoichiometry 45 points Do not turn page until told to do so. Stoichiometry Multiple Choice (Each worth 2 points) Identify the letter of the choice that best completes the statement or

### Outline. 6.1 The Mole and Avogadro s Number. 6.2 Gram Mole Conversions. 6.3 Mole Relationships and Chemical Equations

Outline 6.1 The Mole and Avogadro s Number 6.2 Gram Mole Conversions 6.3 Mole Relationships and Chemical Equations 6.4 Mass Relationships and Chemical Equations 6.5 Limiting Reagent and Percent Yield Goals

### Mole Relationships in Chemistry

Mole Relationships in Chemistry The Mole Concept and Atomic Masses The mole concept and molar mass is historically based on two laws from Joseph-Louis Proust in 1797 The Law of Definite Proportions This

### 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

### 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 10 Chemical Quantities

Chapter 10 Chemical Quantities 101 The Mole: A Measurement 102 Mole-Mass and Mole-Volume Relationships 103 Percent Composition and Chemical Formulas 1 Copyright Pearson Education, Inc, or its affiliates

### Chapter 3: Stoichiometry

Chapter 3: Stoichiometry Goal is to understand and become proficient at working with: 1. Avogadro's Number, molar mass and converting between mass and moles (REVIEW). 2. empirical formulas from analysis.

### The Mole, Avogadro s Number, and Molar Mass

The Mole, Avogadro s Number, and Molar Mass Example: How many atoms are present in 2.0 kg of silver? (1 amu = 1.6605402x10-24 g) Example: How many molecules are present in 10. mg of smelling salts, (NH

### 10.3 Percent Composition and Chemical Formulas

Name Class Date 10.3 Percent Composition and Chemical Formulas Essential Understanding of its empirical formula. A molecular formula of a compound is a whole-number multiple Lesson Summary Percent Composition

### 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

### Ch. 6 Chemical Composition and Stoichiometry

Ch. 6 Chemical Composition and Stoichiometry The Mole Concept [6.2, 6.3] Conversions between g mol atoms [6.3, 6.4, 6.5] Mass Percent [6.6, 6.7] Empirical and Molecular Formula [6.8, 6.9] Bring your calculators!

### 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

### Subscripts and Coefficients Give Different Information

Chapter 3: Stoichiometry Goal is to understand and become proficient at working with: 1. Chemical equations (Balancing REVIEW) 2. Some simple patterns of reactivity 3. Formula weights (REVIEW) 4. Avogadro's

### TOPIC 8. CHEMICAL CALCULATIONS II: % composition, empirical formulas.

TOPIC 8. CHEMICAL CALCULATIONS II: % composition, empirical formulas. Percentage composition of elements in compounds. In Topic 1 it was stated that a given compound always has the same composition by

### EMPIRICAL AND MOLECULAR FORMULA

EMPIRICAL AND MOLECULAR FORMULA Percent Composition: law of constant composition states that any sample of a pure compound always consists of the same elements combined in the same proportions by mass

### 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

### Chemical Reactions. Chemical Arithmetic

Chemical Reactions Chapter 6 Chemical Arithmetic Balancing Equations The mole Gram - mole conversions Mole - mole relationships in chemical equations Mass relationships in chemical equations Per cent yeilds

### 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

### 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

### 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

### 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

### CHEM 120 Online: Chapter 6 Sample problems Date: 2. Which of the following compounds has the largest formula mass? A) H2O B) NH3 C) CO D) BeH2

CHEM 120 Online: Chapter 6 Sample problems Date: 1. To determine the formula mass of a compound you should A) add up the atomic masses of all the atoms present. B) add up the atomic masses of all the atoms

### Sample Exercise 3.1 Interpreting and Balancing Chemical Equations

Sample Exercise 3.1 Interpreting and Balancing Chemical Equations The following diagram represents a chemical reaction in which the red spheres are oxygen atoms and the blue spheres are nitrogen atoms.

### Ch. 10 The Mole I. Molar Conversions

Ch. 10 The Mole I. Molar Conversions I II III IV A. What is the Mole? A counting number (like a dozen) Avogadro s number (N A ) 1 mole = 6.022 10 23 representative particles B. Mole/Particle Conversions

### TOPIC 8. CHEMICAL CALCULATIONS II: % composition, empirical formulas.

TOPIC 8. CHEMICAL CALCULATIONS II: % composition, empirical formulas. Percentage composition of elements in compounds. In Topic 1 it was stated that a given compound always has the same composition by

### CHEM 110: CHAPTER 3: STOICHIOMETRY: CALCULATIONS WITH CHEMICAL FORMULAS AND EQUATIONS

1 CHEM 110: CHAPTER 3: STOICHIOMETRY: CALCULATIONS WITH CHEMICAL FORMULAS AND EQUATIONS The Chemical Equation A chemical equation concisely shows the initial (reactants) and final (products) results of

### CHEM 101/105 Numbers and mass / Counting and weighing Lect-03

CHEM 101/105 Numbers and mass / Counting and weighing Lect-03 Interpretation of Elemental Chemical Symbols, Chemical Formulas, and Chemical Equations Interpretation of an element's chemical symbol depends

The Mole and Chemical Table of Contents Chemical Formulas Bellringer List as many common counting units as you can. Determine how many groups of each unit in your list are present in each of the following

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

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

### 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

### 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

### CHEM 100 Principles Of Chemistry. Chapter 5 - How Chemists Measure Atoms & Molecules

CHEM 100 Principles Of Chemistry Chapter 5 - How Chemists Measure Atoms & Molecules 5.1 Weighing Objects to Count Objects When coin parking meters are emptied, the coins are not counted but weighed By

### 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