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

Size: px
Start display at page:

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

Transcription

1 Introductory Chemistry: A Foundation FOURTH EDITION by Steven S. Zumdahl University of Illinois Chemical Composition Chapter Atomic Masses Balanced equation tells us the relative numbers of molecules of reactants and products C + O 2 CO 2 1 atom of C reacts with 1 molecule of O 2 to make 1 molecule of CO 2 If I want to know how many O 2 molecules I will need or how many CO 2 molecules I can make, I will need to know how many C atoms are in the sample of carbon I am starting with Atomic Masses Dalton used the percentages of elements in compounds and the chemical formulas to deduce the relative masses of atoms Unit is the amu. atomic mass unit 1 amu 1.66 x g We define the masses of atoms in terms of atomic mass units 1 Carbon atom amu, 1 Oxygen atom amu 1 O 2 molecule 2(16.00 amu) 2.00 amu 4 Atomic Masses Example #1 Calculate the Mass (in amu) of 75 atoms of Al Atomic masses allow us to convert weights into numbers of atoms If our sample of carbon weighs.00 x amu we will have 2.50 x atoms of carbon 20 1C atom x 10 amu x 2.50 x 10 C atoms 12.01amu Since our equation tells us that 1 C atom reacts with 1 O 2 molecule, if I have 2.50 x C atoms, I will need 2.50 x molecules of O 2 5 Determine the mass of 1 Al atom 1 atom of Al amu Use the relationship as a conversion factor amu 75 Al atoms x 2024 amu 1 Al atom 6

2 Chemical Packages - Moles The MOLE We use a package for atoms and molecules called a mole A mole is the number of particles equal to the number of Carbon atoms in 12 g of C-12 One mole x 10 2 units The number of particles in 1 mole is called Avogadro s Number 1 mole of C atoms weighs g and has 6.02 x 10 2 atoms 7 8 The Mole When two chemicals react with each other, we want to know how many atoms or molecules of each are used do that a formula of the product can be established. This means we need a way to count atoms, but HOW? The solution to this problem is to define a convenient unit of matter that contains a know number of particles. 1 moles particles This value is commonly known has Avogadro s number. Remember that one mole always contains the same number of particles, no matter what the substance. Molar Mass The mass of one mole of atoms of any element is the molar mass, which is numerically equal to the atomic mass, but in grams. Example: 1 mole of sodium weighs g This not only true for atoms, but also for molecules, but we use the molecular mass instead of the atomic mass. To determine the molecular mass of a molecule, we add up the atomic masses of the elements that make up the molecule. Example: CCl 4» We have 1 carbon and 4 chlorines» g/mol + 4( g/mol) g/mol» Therefore, if we have 1 mole of CCl 4 it would weigh g Molecules, Compounds, and The Mole Thinking about moles with respect to molecules and compounds is not all that different than with atoms. If I have 1 mole of CH 4: 1. How many CH 4 molecules do I have? I have molecules of CH 4 2. How much does it weigh? g. How many carbon atoms do I have? How many hydrogen atoms do I have? MOLES are the CENTER # of particles a) Multiply by Avogadro s Number b) Divide by Avogadro s Number c) Multiply by the molecular weight of X d) Divide by the molecular weight of X a b # of moles of X c Mass d e f Vol. of an ideal STP e) Multiply by 22.4 L / mol f) Divide by 22.4 L / mol

3 What is the mass, in grams, of 1.5 mols of silicon? g How many moles are represented by 454 g of sulfur? How many atoms? 14.2 mols atoms EXAMPLES At first these concepts are difficult to understand, but working problems is the best way to become comfortable with these concepts. Calculate the molar mass of CaCO (limestone) g/mol If you have 454 g of CaCO, how many moles do you have? How many molecules? How many atoms of oxygen? 4.54 mols molecules atom of O 1 Example #2 and number of atoms in 10.0 g of Al Use the Periodic Table to determine the mass of 1 mole of Al 1 mole Al g grams-to-moles 1 mol Al 10.0 g Al x 0.71 mol Al g 14 and number of atoms in 10.0 g of Al Use Avogadro s Number to determine the number of atoms in 1 mole 1 mole Al 6.02 x 10 2 atoms moles-to-atoms 0.71 mol Al x Example # x 10 atoms 2.2 x 10 1 mol Al 2 Al atoms Example # and mass of 2.2 x 10 2 atoms of Al Use Avogadro s Number to determine the number of atoms in 1 mole 1 mole Al 6.02 x 10 2 atoms atoms-to-moles 2 1molAl 2.2x 10 Alatoms x 0.70molAl x 10 atoms Example # and mass of 2.2 x 10 2 atoms of Al Use the Periodic Table to determine the mass of 1 mole of Al 1 mole Al g moles-to-grams g 0.70 mol Al x 9.99 g Al 1 mol Al Molar Mass The molar mass is the mass in grams of one mole of a compound The relative weights of molecules can be calculated from atomic masses water H 2 O 2(1.008 amu) amu amu 1 mole of H 2 O will weigh g, therefore the molar mass of H 2 O is g 1 mole of H 2 O will contain g of oxygen and 2.02 g of hydrogen 17 18

4 Percent Composition Percentage of each element in a compound By mass Can be determined from the formula of the compound or the experimental mass analysis of the compound The percentages may not always total to 100% due to rounding part Percentage 100% whole 19 Percent Composition Percent Composition The percentage of the mass of a compound represented by each of its constituent elements. According to the law of constant composition, any sample of a pure compound always consists of the same elements combined in the same proportion by mass. Example: What is the percent composition of N and H in ammonia (NH )? Mass Percent N in NH Mass of N in 1 mol of NH g N 100 Mass of 1 mol of NH 17.0 g NH 82.27% Mass Percent H in NH Mass of H in 1 mol of NH (1.008) g H 100 Mass of 1 mol of NH 17.0 gnh 17.76% 20 Empirical and Molecular Formulas We have discussed molecular formulas Empirical formulas A molecular formula showing the simplest possible ratio of atoms in a molecule. From percent compositions we can determine empirical and molecular formulas by the following procedure. x mol A % A g A x mols A % B g B x mols B Find mole y mol B ratio Ratio gives formula A x B y 21 Example Eugenol is the active component of oil of cloves. It has a molar mass of g/mol and is 7.14% C and 7.7% H; the remainder is oxygen. What are empirical and molecular formulas for eugenol? Where to start?! 1. What is the % of oxygen? 100% - (7.14% + 7.7%) 19.49% 2. How many grams of C, H, and O? Assume you have 100 g of the compound therefore your percentages are the number of grams of C, H, and O g of C 7.7 g of H g of O. Change the grams into moles g of C 1 mole of C / g of C 6.09 mols of C 7.7 g of H 1 mole of H / g of H 7.1 mols of H g of O 1 mole of O / g of O 1.22 mols of O 4. Find the mole ratios (divide the large amount(s) of moles by the smallest amount of moles) mols of C / 1.22 mols of O 5 mols of C to 1 mol of O 7.7 mols of H / 1.22 mols of O 6 mols of H to 1 mol of O 5. So what does this mean? C 5 H 6 O is the 6. How to get the molecular formula? Molecular weight of the. 82 g/mol Divide the molecular weight of eugenol by the molecular weight g/mol / 82 g/mol 2 So there are 2 units of the. (C 5H 6O) 2 C 10H 12O 2 22 Hydrated Compounds If ionic compounds are prepared water solution and then isolated as solids, the crystals often have molecules of water trapped in the lattice. Compounds in which molecules of water are associated with the ions of the compound are called hydrated compounds. Examples: NiCl 2 6H 2 O CaSO 4 2H 2 O But what about the molar mass? (Do I add the water?) YES! NiCl 2 6H 2 O 27.7 g/mol g/mol from NiCl g/mol from 6H 2 O CaSO 4 2H 2 O g/mol 2 Determining the Units of Hydration Example: The following reaction takes place g of CuSO 4 x H 2 O + heat g CuSO 4 +? g H 2 O Find the units of hydration. Step 1: determine the mass of water 1.02 g of CuSO 4 x H 2 O g of CuSO g of water Step 2: determine the number of moles 0.69 g of water 1 mol of water / g of water mols of water g CuSO 4 1 mols CuSO 4 / g CuSO mols CuSO 4 Step : determine the molar ratio mol H O mol CuSO mol CuSO So, we know that we started with 1.02 g of CuSO 4 5 H 2 O mol H O

5 Example #4 Determine the Percent Composition from the Formula C 2 H 5 OH Determine the mass of each element in 1 mole of the compound 2 moles C 2(12.01 g) g 6 moles H 6(1.008 g) g 1 mol O 1(16.00 g) g Determine the molar mass of the compound by adding the masses of the elements 1 mole C 2 H 5 OH g Example #4 Determine the Percent Composition from the Formula C 2 H 5 OH Divide the mass of each element by the molar mass of the compound and multiply by 100% 24.02g 100% 52.14%C 46.07g 6.048g 100% 1.1%H 46.07g 16.00g 100% 4.7%O 46.07g Empirical Formulas The simplest, whole-number ratio of atoms in a molecule is called the Empirical Formula can be determined from percent composition or combining masses The Molecular Formula is a multiple of the Empirical Formula MM A % A mass A (g) moles A MM B moles A moles B % B mass B (g) moles B Example #5 Benzopyrene, C 20 H 12 Find the greatest common factor (GCF) of the subscripts factors of 20 (10 x 2), (5 x 4) factors of 12 (6 x 2), (4 x ) GCF 4 Divide each subscript by the GCF to get the C 20 H 12 (C 5 H ) 4 Empirical Formula C 5 H Convert the percentages to grams by assuming you have 100 g of the compound Step can be skipped if given masses 47gC 47gC 47gO 6.0gH 47gO 6.0gH Convert the grams to moles 1mol C 47g C.9 mol C 12.01g 1mol H 6.0 g H 6.0 mol H 1.008g 1 mol O 47 g O 2.9 mol O 16.00g 29 0

6 Divide each by the smallest number of moles.9 mol C mol H mol O If any of the ratios is not a whole number, multiply all the ratios by a factor to make it a whole number If ratio is?.5 then multiply by 2; if?. or?.67 then multiply by ; if?.25 or?.75 then multiply by 4 Multiply all the Ratios by Because C is 1..9 mol C x mol H x mol O x 1 2 Use the ratios as the subscripts in the.9 mol C x mol H x mol O x C 4 H 6 O Molecular Formulas The molecular formula is a multiple of the To determine the molecular formula you need to know the and the molar mass of the compound 4 Example #7 Determine the Molecular Formula of Benzopyrene if it has a molar mass of 252 g and an of C 5 H Determine the May need to calculate it as previous C 5 H Determine the molar mass of the empirical formula 5 C g, H.024 g C 5 H 6.07 g Example #7 Determine the Molecular Formula of Benzopyrene if it has a molar mass of 252 g and an of C 5 H Divide the given molar mass of the compound by the molar mass of the Round to the nearest whole number 252g 6.07g 4 5 6

7 Example #7 Determine the Molecular Formula of Benzopyrene if it has a molar mass of 252 g and an of C 5 H Multiply the by the calculated factor to give the molecular formula (C 5 H ) 4 C 20 H 12 Homework Questions and Problems: 6, 12, 14, 16, 18, 20, 22, 24, 26, 28, 0, 2, 4, 6, 8, 40, 42, 44, 46, 48, 50, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82,

### 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.

### 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

### 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 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,

### 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

### 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

### 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

### 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

### The Mole Notes. There are many ways to or measure things. In Chemistry we also have special ways to count and measure things, one of which is the.

The Mole Notes I. Introduction There are many ways to or measure things. In Chemistry we also have special ways to count and measure things, one of which is the. A. The Mole (mol) Recall that atoms of

### 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

### = 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

### 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

### 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

### 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

### 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

### 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

### 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

### 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?

### 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

### 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

### 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

### MOLECULAR MASS AND FORMULA MASS

1 MOLECULAR MASS AND FORMULA MASS Molecular mass = sum of the atomic weights of all atoms in the molecule. Formula mass = sum of the atomic weights of all atoms in the formula unit. 2 MOLECULAR MASS AND

### Chapter 6 Notes. Chemical Composition

Chapter 6 Notes Chemical Composition Section 6.1: Counting By Weighing We can weigh a large number of the objects and find the average mass. Once we know the average mass we can equate that to any number

### 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

### 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!

### 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

### 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

### 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

### Chapter 8 How to Do Chemical Calculations

Chapter 8 How to Do Chemical Calculations Chemistry is both a qualitative and a quantitative science. In the laboratory, it is important to be able to measure quantities of chemical substances and, as

### 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

### 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

### 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

### 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

### 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?

### 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

### 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

### 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

### 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

### 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.

### 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

### 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

### 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

### 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

### 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 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

### The Mole. 6.022 x 10 23

The Mole 6.022 x 10 23 Background: atomic masses Look at the atomic masses on the periodic table. What do these represent? E.g. the atomic mass of Carbon is 12.01 (atomic # is 6) We know there are 6 protons

### 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

### EXPERIMENT 12: Empirical Formula of a Compound

EXPERIMENT 12: Empirical Formula of a Compound INTRODUCTION Chemical formulas indicate the composition of compounds. A formula that gives only the simplest ratio of the relative number of atoms in a compound

### MOLES, MOLECULES, FORMULAS. Part I: What Is a Mole And Why Are Chemists Interested in It?

NAME PARTNERS SECTION DATE_ MOLES, MOLECULES, FORMULAS This activity is designed to introduce a convenient unit used by chemists and to illustrate uses of the unit. Part I: What Is a Mole And Why Are Chemists

### 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

### 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

### 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

### 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

### 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

### 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

### How To Calculate Mass In Chemical Reactions

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

### 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

### 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

Page 1 of 14 Amount of Substance Key terms in this chapter are: Element Compound Mixture Atom Molecule Ion Relative Atomic Mass Avogadro constant Mole Isotope Relative Isotopic Mass Relative Molecular

### 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 3-1 Chapter 3 Stoichiometry In This Chapter As you have learned in previous chapters, much of chemistry involves using macroscopic measurements to deduce what happens between atoms

### 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

### 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.

### 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

### 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 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 Composition Review Mole Calculations Percent Composition Copyright Cengage Learning. All rights reserved. 8 1 QUESTION Suppose you work in a hardware store and a customer wants to purchase 500

### 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

### 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

### SYMBOLS, FORMULAS AND MOLAR MASSES

SYMBOLS, FORMULAS AND MOLAR MASSES OBJECTIVES 1. To correctly write and interpret chemical formulas 2. To calculate molecular weights from chemical formulas 3. To calculate moles from grams using chemical

### 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

### 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

### 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

### Chemical formulae are used as shorthand to indicate how many atoms of one element combine with another element to form a compound.

29 Chemical Formulae Chemical formulae are used as shorthand to indicate how many atoms of one element combine with another element to form a compound. C 2 H 6, 2 atoms of carbon combine with 6 atoms of

### Mole Calculations Multiple Choice Review PSI Chemistry

Mole Calculations Multiple Choice Review PSI Chemistry Name The Mole and Avogadro's Number 1)What is the SI unit for measurement of number of particles in a substance? A) kilogram B) ampere C) candela

### 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

### 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.

### 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

### 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)

### 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

### 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

### 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

### Molar Mass Worksheet Answer Key

Molar Mass Worksheet Answer Key Calculate the molar masses of the following chemicals: 1) Cl 2 71 g/mol 2) KOH 56.1 g/mol 3) BeCl 2 80 g/mol 4) FeCl 3 162.3 g/mol 5) BF 3 67.8 g/mol 6) CCl 2 F 2 121 g/mol

### 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.

### General Chemistry I (FC, 09-10) Lab #3: The Empirical Formula of a Compound. Introduction

General Chemistry I (FC, 09-10) Introduction A look at the mass relationships in chemistry reveals little order or sense. The ratio of the masses of the elements in a compound, while constant, does not

### 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

### 2 The Structure of Atoms

CHAPTER 4 2 The Structure of Atoms SECTION Atoms KEY IDEAS As you read this section, keep these questions in mind: What do atoms of the same element have in common? What are isotopes? How is an element

### 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.

### Experiment 8: Chemical Moles: Converting Baking Soda to Table Salt

Experiment 8: Chemical Moles: Converting Baking Soda to Table Salt What is the purpose of this lab? We want to develop a model that shows in a simple way the relationship between the amounts of reactants

### 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

### CH3 Stoichiometry. The violent chemical reaction of bromine and phosphorus. P.76

CH3 Stoichiometry The violent chemical reaction of bromine and phosphorus. P.76 Contents 3.1 Counting by Weighing 3.2 Atomic Masses 3.3 The Mole 3.4 Molar Mass 3.5 Percent Composition of Compounds 3.6

### What s in a Mole? Molar Mass

LESSON 10 What s in a Mole? Molar Mass OVERVIEW Key Ideas Lesson Type Lab: Groups of 4 Chemists compare moles of substances rather than masses because moles are a way of counting atoms. When considering

Contents Getting the most from this book...4 About this book....5 Content Guidance Topic 1 Atomic structure and the periodic table...8 Topic 2 Bonding and structure...14 Topic 2A Bonding....14 Topic 2B

### The Empirical Formula of a Compound

The Empirical Formula of a Compound Lab #5 Introduction A look at the mass relationships in chemistry reveals little order or sense. The ratio of the masses of the elements in a compound, while constant,

### Lecture 3: (Lec3A) Atomic Theory

Lecture 3: (Lec3A) Atomic Theory Mass of Atoms Sections (Zumdahl 6 th Edition) 3.1-3.4 The Concept of the Mole Outline: The mass of a mole of atoms and the mass of a mole of molecules The composition of

### 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

### 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