Chapter 6 Notes. Chemical Composition

Size: px
Start display at page:

Download "Chapter 6 Notes. Chemical Composition"

Transcription

1 Chapter 6 Notes Chemical Composition

2 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 of the objects. EXAMPLE: The average mass of a book is 40.0 grams. How many books are present in a sample with a mass of grams? g/40.0g = 50.0 books 6-2

3 Counting By Weighing When we know the average mass of the atoms of an element, as that element occurs in nature, we can calculate the number of atoms in any given sample of that element by weighing the sample. The atomic mass of an element, as found on the periodic table, allows us to count by weighing. 6-3

4 Section 6.2: Atomic Masses Atoms are very small, a single carbon atom has a mass of 1.99 x grams ( g). So, scientists had to come up with a smaller unit to measure their mass: the atomic mass unit (amu). 1 amu = 1.66 x grams According to the periodic table, the average mass of a carbon atom is amu. 6-4

5 Section 6.3: The Mole Not this type of mole! The mole (mol) is known as the chemists dozen and represents x things (atoms, particles, molecules, etc). Just as we could have a dozen donuts, we could also have a mole of donuts; that d be A LOT of donuts! 6-5

6 The Mole: Interesting Mole Facts X watermelon seeds: would be found inside a melon slightly larger than the moon. 6-6

7 6.02 X grains of sand: would be more than all of the sand on Miami Beach.

8 6.022 X pennies: would make at least 7 stacks that would reach the moon X blood cells: would be more than the total number of blood cells found in every human on earth. A mol is A LOT of particles: 602,200,000,000,000,000,000,000

9 The Mole It is VERY important to understand that the value listed as the mass number on the periodic table really tells us TWO things: The mass of one atom in units of amu s. The mass of one mole of atoms in grams. One mol of Al = g & one atom = amu One mol of Au = g & one atom = amu One mol of B = g & one atom = amu Remember one mol = X atoms (or particles or molecules) 6-9

10 The Mole To summarize: a sample of any element that weighs a number of grams equal to the average atomic mass (from the periodic table) contains x atoms (1 mol) of that element. Therefore, atomic weight of an element = #g in one mol of that element We write that as g/mol. 6-10

11 Using the mol in calculations How many mols are in 7.0 g of N? 7.0 g 1 mol = 0.50 mol 1 14 g How many atoms are in 7.0 g of N? (0.5mol)( x 1023 atoms / 1 mol )= x atoms. OR (7.0 g)( 1 mol / 14.0 g )( x 1023 atoms / 1 mol )=3.011 x atoms

12 The Mole: Practice 1) Calculate the number of moles and the number of atoms in a 25.0 g sample of calcium. 2) Calculate the number of moles and the number of atoms in a 57.7 g sample of sulfur. 3) Calculate the number of atoms in a 23.6 mg sample of zinc. 4) Calculate the number of atoms in a mg sample of silver. 6-12

13 mol and 3.76 x atoms mol and 1.08 x atoms x 10-4 mol and 2.17 x atoms x 10-3 mol and x atoms

14 The Mole: More Interesting Mole Facts A one-liter bottle of water contains 55.5 moles H 2 0 molecules. A five-pound bag of sugar contains 6.6 moles of C 12 H 22 O 11 (sucrose). We have 3 types of moles that live underground in North America: Eastern Mole, Hairy-Tailed Mole and Star-Nosed Mole The "Mexican" Mole is a chocolate sauce or turkey stew. It comes from the Aztec word "molli." 6-14

15 Section 6.4: Molar Mass A chemical compound is a collection of atoms. One methane (CH 4 ) molecule contains one C atom and four H atoms. It follows then that one mole of methane molecules contains one mole of C atoms and four moles of H atoms. 6-15

16 Figure 6.3: Various numbers of methane molecules. 6-16

17 Molar Mass (g/mol) The molar mass of any substance is the mass (in grams) of one mole of the substance. The molar mass of a compound is obtained by summing the masses of ALL component atoms. The term formula weight may be used for ionic compounds and is analogous to molecular weight; both are molar masses. 6-17

18 Molar Mass If we know how many atoms and how many moles are present, we can calculate the mass of one mole of a compound. This is called the molar mass or sometimes you may also see it referred to as molecular weight. Since 1 mol C = g and 4 mol H = 4(1.008) or g, 1 mol CH 4 = or g (sig figs). Remember to use mass numbers from the periodic table. 6-18

19 Molar Mass Remember: we can talk about one mole of atoms or one mole of molecules. One mole of oxygen atoms (O) weighs g. One mole of oxygen molecules (O 2 ) weighs g. Two moles of O atoms weigh g. Two moles of O 2 molecules weigh g. And so on

20 Molar Mass: Practice 1) Calculate the following molar masses: a) Water H 2 O b) Ammonia NH 3 c) Propane C 3 H 8 d) Glucose C 6 H 12 O 6 2) Calculate the mass of 1.48 mol C 3 H 8. 3) Calculate the mass of 4.85 mol HC 2 H 3 O

21 Molar Mass: Practice 1. Calculate the number of moles of H 2 CO 3 present in a 7.55 g sample. 2. Calculate the number of moles of tetraphosphorous decoxide present in a g sample. 3. How many water molecules are present in 10.0 g of water? (Hint: find moles first) 4. How many molecules of sucrose (C 12 H 22 O 11 ) are present in a five pound bag of sugar? 6-21

22 Representative Particles= atoms, molecules, Items, etc

23 Section 6.5: Percent Composition of Compounds Sometimes it is not enough to know a compound s composition in terms of numbers of atoms; it may also be useful to know its composition in terms of the masses of its elements. We can calculate the mass fraction by dividing the mass of a given element in one mole of a compound by the mass of one mole of the compound. 6-23

24 Percent Composition of Compounds Once we know the mass fraction we can multiply by 100 to get the percent. Remember: percent = part/whole X

25 ex) In one mole of methane (CH 4 ), there is one mole of C and four moles of H: 1 mol C = g 4 mol H = 4(1.008) = g 1 mol CH 4 = g g = g %C= mass of 1mol C/ mass of 1 mol CH 4 x 100 %C = 12.01/ X 100 = 74.87% C %H= mass of 4 mol H/mass of 1 mol CH 4 x 100 %H = 4.032/ X 100 = 25.13% H

26 Percent Composition Practice Determine the mass percent of each element in the following: H 2 SO 4 (sulfuric acid) C 3 H 7 OH (isopropyl alcohol) C 6 H 12 O 6 (glucose) 6-26

27 Section 6.6: Formulas of Compounds The object of this section is to do the opposite of the previous section. Instead of getting the mass from the formula, we will determine the formula from the mass. To do this, the mass must be converted to moles using each element s mass number. How can we convert mass to moles? 6-27

28 Formulas of Compounds ex) An unknown compound with a mass of g is is found to contain: g C g H g O It must contain: g (1 mol C/12.01 g C) = mol C g(1 mol H/1.008 g H) = mol H g(1 mol/16.00 g O) = mol O 6-28

29 The numbers from the previous slide allow us to determine the C:H:O ratio (C) : (H) : (O) If we divide each number by the smallest number we get 1:2:1 for the C:H:O ratio. This leads us to a formula of C 1 H 2 O 1 or CH 2 O. This is not necessarily the TRUE formula of the compound, but represents the RELATIVE numbers of atoms. 6-29

30 This represents the lowest whole number ratio of the compound. The actual formula could be CH 2 O, C 2 H 4 O 2, C 3 H 6 O 3, C 4 H 8 O 4, C 5 H 10 O 5, C 6 H 12 O 6,... Any formula with a C:H:O ratio of 1:2:1 is possible (in theory, an infinite number). C 1 H 2 O 1 represents the simplest possible formula or the EMPIRICAL FORMULA. The multiples represent possible MOLECULAR FORMULAS. 6-30

31 Formulas of Compounds: Practice Determine the empirical formula from each of the following molecular formulas: H 2 O 2 (hydrogen peroxide) C 4 H 10 (butane) CCl 4 (name?) HC 2 H 3 O 2 (acetic acid) C 6 H 12 O 6 (glucose) 6-31

32 Section 6.7: Calculation of Empirical Formulas There are four steps to determine the empirical formula of a compound: 1. Obtain the mass of each element present (in grams). 2. Determine the number of moles of each type of atom present (use atomic mass). 3. Divide each number by the smallest number. 4. Multiply all numbers by the smallest integer that will make them all integers 6-32

33 Empirical Formulas: Practice 1) A g sample of a compound containing only carbon and hydrogen is found to contain g of carbon. Determine the empirical formula for this compound. 2) A g sample of nitrogen reacts with g of oxygen. Determine the empirical formula for this compound. 3) When a g sample of iron metal is heated in air, it reacts with oxygen to achieve a final mass of 2.573g. Determine the empirical formula for this compound. 6-33

34 If the relative amounts of elements are presented as percentages, assume we are starting with a 100 g sample (100%). Then each percentage simply becomes a mass (in grams). For example if 15% of a compound is carbon, we just assume it is 15 g of a 100 g sample; from there we convert to moles. 6-34

35 Empirical Formulas: More Practice 1) The simplest amino acid, glycine, has the following mass percents: 32.00% carbon, 6.714% hydrogen, 42.63% oxygen, and 18.66% nitrogen. Determine the empirical formula for glycine. 2) A compound has been analyzed and found to have the following mass percent composition: 66.75% copper, 10.84% phosphorous, and 22.41% oxygen. Determine the empirical formula for this compound. 6-35

36 Section 6.8: Calculation of Molecular Formulas If we know the empirical formula AND the molar mass, we can calculate a compound s molecular formula. Note: without the molar mass, the best you can find is the empirical formula. Once the molar mass is known, one must ALWAYS find the empirical formula before one can calculate the molecular formula. It is impossible to do the reverse. 6-36

37 Calculation of Molecular Formulas It is also important to note that the molecular formula is ALWAYS an integer multiple of the empirical formula. We can represent the molecular formula in terms of the empirical formula: (Empirical Formula) n = molecular formula It should also be noted when n = 1, the empirical and molecular formulas are identical to each other. 6-37

38 Molecular Formulas: Practice 1) A compound containing carbon, hydrogen, and oxygen is found to be 40.00% carbon and 6.700% hydrogen by mass. The molar mass of this compound is between 115 and 125 g/mol. Determine the molecular formula for this compound. 2) Caffeine is composed of 49.47% C, 5.191% H, 28.86% N, and 16.48% O. The molar mass is about 194 g/mol. Determine the molecular formula for caffeine. 6-38

Chapter 10 Chemical Quantities

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

More information

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. 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

More information

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

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.

More information

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. 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

More information

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

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

More information

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

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

More information

Mass and Moles of a Substance

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

More information

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

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

More information

Practice questions for Ch. 3

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

More information

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

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

More information

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.

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

More information

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

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

More information

Ch. 10 The Mole I. Molar Conversions

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

More information

CHAPTER 8: CHEMICAL COMPOSITION

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

More information

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) 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.

More information

Formula Stoichiometry. Text pages

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

More information

The Mole Concept. The Mole. Masses of molecules

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

More information

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?

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

More information

Solution. Practice Exercise. Concept Exercise

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

More information

INTRODUCTORY CHEMISTRY Concepts and Critical Thinking

INTRODUCTORY CHEMISTRY Concepts and Critical Thinking INTRODUCTORY CHEMISTRY Concepts and Critical Thinking Sixth Edition by Charles H. Corwin Chapter 9 The Mole Concept by Christopher Hamaker 2011 Pearson Education, Inc. Chapter 9 1 Avogadro s Number Avogadro

More information

Chapter 7. Bellringer. Table of Contents. Chapter 7. Chapter 7. Objectives. Avogadro s Number and the Mole. Chapter 7. Chapter 7

Chapter 7. Bellringer. Table of Contents. Chapter 7. Chapter 7. Objectives. Avogadro s Number and the Mole. Chapter 7. Chapter 7 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

More information

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

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

More information

Unit 3 Notepack Chapter 7 Chemical Quantities Qualifier for Test

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?

More information

Name Block THE MOLE. Who s Counting Lab. Mole Notes. Mole Calculations. Mixed Mole Conversions. % Comp, Emp, and Molecular Calcuations

Name Block THE MOLE. Who s Counting Lab. Mole Notes. Mole Calculations. Mixed Mole Conversions. % Comp, Emp, and Molecular Calcuations Name Block THE MOLE Who s Counting Lab Mole Notes Mole Calculations Mixed Mole Conversions % Comp, Emp, and Molecular Calcuations Mole Notes, Part 1 1. The Mole is just a long word for changing units

More information

Chemistry 65 Chapter 6 THE MOLE CONCEPT

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

More information

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

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

More information

CHEMICAL QUANTITIES. Chapter 10

CHEMICAL QUANTITIES. Chapter 10 CHEMICAL QUANTITIES Chapter 10 What is a mole? A unit of measurement in chemistry 1 mole of a substance = 6.02 x 10 23 (Avagadro s number) representative particles of a substance Representative particle

More information

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

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

More information

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

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

More information

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. 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

More information

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

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

More information

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

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,

More information

Lecture 5, The Mole. What is a mole?

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?

More information

Chapter Three: STOICHIOMETRY

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

More information

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 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,

More information

CHAPTER 11 - CHEMICAL QUANTITIES

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

More information

Chapter 6: Chemical Composition. Molar Mass and Percent Composition

Chapter 6: Chemical Composition. Molar Mass and Percent Composition Chapter 6: Chemical Composition Molar Mass and Percent Composition Learning Targets You will learn to use molar mass to calculate percent composition. Mass Average atomic mass is the weighted average of

More information

Notes: Formula Mass and Percent Composition

Notes: Formula Mass and Percent Composition Notes: Formula Mass and Percent Composition Formula mass - the mass of one mole of a compound, atom or ion. -also called: gram formula mass, molecular mass, gram molecular mass, formula weight, gram formula

More information

Chapter 6 Chemical Calculations

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

More information

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

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

More information

Introductory Chemistry Fourth Edition Nivaldo J. Tro

Introductory Chemistry Fourth Edition Nivaldo J. Tro Introductory Chemistry Fourth Edition Nivaldo J. Tro Chapter 6 Chemical Composition Dr. Sylvia Esjornson Southwestern Oklahoma State University Weatherford, OK 6.1 How Much Sodium? Sodium is an important

More information

Study Guide For Chapter 7

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

More information

2/15/2013. Chapter

2/15/2013. Chapter Chapter 10 1 10.1 You could measure the amount of sand in a sand sculpture by counting each grain of sand, but it would be much easier to weigh the sand. You ll discover how chemists measure the amount

More information

10.3 Percent Composition and Chemical Formulas

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

More information

Chapter 4 Chemical Composition

Chapter 4 Chemical Composition Chapter 4 Chemical Composition 4.1 (a) mole; (b) Avogadro s number; (c) empirical formula; (d) solute; (e) molarity; (f) concentrated solution 4. (a) molar mass; (b) percent composition by mass; (c) solvent;

More information

Percent Composition. Percent Composition the percentage by mass of each element in a compound. Percent = Part Whole x 100%

Percent Composition. Percent Composition the percentage by mass of each element in a compound. Percent = Part Whole x 100% Percent Composition Percent Composition the percentage by mass of each element in a compound Percent = Part Whole x 100% Percent composition of a compound or = molecule Mass of element in 1 mol x 100%

More information

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

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

More information

Chapter 6: Chemical Composition

Chapter 6: Chemical Composition C h e m i s t r y 1 2 C h 6 : C h e m i c a l C o m p o s i t i o n P a g e 1 Chapter 6: Chemical Composition Bonus: 17, 21, 31, 39, 43, 47, 55, 61, 63, 69, 71, 77, 81, 85, 91, 95, 97, 99 Check the deadlines

More information

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

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

More information

= 16.00 amu. = 39.10 amu

= 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

More information

TUTORIAL 5-1 HELP. Mass of sodium = 23.0 g/mol x 3 mol = 69.0 g of sodium. Percent mass of sodium = 69.0 g x 100% = 42.

TUTORIAL 5-1 HELP. Mass of sodium = 23.0 g/mol x 3 mol = 69.0 g of sodium. Percent mass of sodium = 69.0 g x 100% = 42. TUTORIAL 5-1 HELP ANSWER TO QUESTION 1 ON TUTORIAL 5-1: Question 1. Find the percent composition by mass of sodium phosphate, Na 3 PO 4. Step 1: Find the molar mass of Na 3 PO 4 (The mass of one mole of

More information

Mole Notes.notebook. October 29, 2014

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

More information

Chapter 5. Quantities in Chemistry

Chapter 5. Quantities in Chemistry Chapter 5 Quantities in Chemistry REMEMBER: You are required to use dimensional analysis whenever possible, which is almost all of the time in chemistry! If you choose not to use dimensional analysis,

More information

SCH 4C1 Unit 2 Problem Set Questions taken from Frank Mustoe et all, "Chemistry 11", McGraw-Hill Ryerson, 2001

SCH 4C1 Unit 2 Problem Set Questions taken from Frank Mustoe et all, Chemistry 11, McGraw-Hill Ryerson, 2001 SCH 4C1 Unit 2 Problem Set Questions taken from Frank Mustoe et all, "Chemistry 11", McGraw-Hill Ryerson, 2001 1. A small pin contains 0.0178 mol of iron. How many atoms of iron are in the pin? 2. A sample

More information

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

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

More information

Chapter 3: Stoichiometry

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

More information

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

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

More information

Formulas, Equations and Moles

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

More information

Sample Exercise 3.1 Interpreting and Balancing Chemical Equations

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.

More information

Stoichiometry Dr. M. E. Bridge

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 )

More information

10 The Mole. Section 10.1 Measuring Matter

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.

More information

Ch. 6 Chemical Composition and Stoichiometry

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!

More information

Unit 5 Chemical Quantities & The Mole

Unit 5 Chemical Quantities & The Mole Unit 5 Chemical Quantities & The Mole Molar mass is the mass of one mole of a substance. Molar Mass Other names for molar mass include *formula mass *gram formula mass *molecular weight Molar Mass One

More information

Chemical Composition Review Mole Calculations Percent Composition. Copyright Cengage Learning. All rights reserved. 8 1

Chemical Composition Review Mole Calculations Percent Composition. Copyright Cengage Learning. All rights reserved. 8 1 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

More information

Lecture 4: (Lec 3B) Stoichiometry

Lecture 4: (Lec 3B) Stoichiometry Lecture 4: (Lec 3B) Stoichiometry Sections (Zumdahl 6 th Edition) 3.6-3.7 Outline: Mass Composition of Molecules Conservation of Atoms (Modern version of the law of definite proportions) Balancing Chemical

More information

Ch09. Formulas. Exploring the molecular blueprint. How we represent compounds & molecules. version 1.5

Ch09. Formulas. Exploring the molecular blueprint. How we represent compounds & molecules. version 1.5 Ch09 Formulas Exploring the molecular blueprint. How we represent compounds & molecules. version 1.5 Nick DeMello, PhD. 2007-2015 Chemical Formulas Molecules & Compounds Compounds are not mixtures. Chemical

More information

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

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

More information

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

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

More information

EMPIRICAL AND MOLECULAR FORMULA

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

More information

Mole Relationships in Chemistry

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

More information

Calculation of Molar Masses. Molar Mass. Solutions. Solutions

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

More information

4. Magnesium has three natural isotopes with the following masses and natural abundances:

4. Magnesium has three natural isotopes with the following masses and natural abundances: Exercise #1 Atomic Masses 1. The average mass of pennies minted after 1982 is 2.50 g and the average mass of pennies minted before 1982 is 3.00 g. In a sample that contains 90.0% new and 10.0% old pennies,

More information

Chapter 7. Chapter 7. Chemical Formulas Express Composition. Chapter 7 MARCH REVIEW SLIDES LISTEN AND UPDATE MISSING NOTES

Chapter 7. Chapter 7. Chemical Formulas Express Composition. Chapter 7 MARCH REVIEW SLIDES LISTEN AND UPDATE MISSING NOTES REVIEW Express A compound s chemical formula tells you which elements, & how much of each, are present in a compound. Formulas for covalent compounds show the elements and the number of atoms of each element

More information

2 The Structure of Atoms

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

More information

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

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

More information

MOLECULAR MASS AND FORMULA MASS

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

More information

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. 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

More information

Chemical Proportions in Compounds

Chemical Proportions in Compounds Chapter 6 Chemical Proportions in Compounds Solutions for Practice Problems Student Textbook page 201 1. Problem A sample of a compound is analyzed and found to contain 0.90 g of calcium and 1.60 g of

More information

Chemical Quantities: The Mole Chapter 7 Assignment & Problem Set

Chemical Quantities: The Mole Chapter 7 Assignment & Problem Set Chemical Quantities: The Mole Name Warm-Ups (Show your work for credit) Date 1. Date 2. Date 3. Date 4. Date 5. Date 6. Date 7. Date 8. Chemical Quantities: The Mole 2 Study Guide: Things You Must Know

More information

Chapter 7 Part II: Chemical Formulas and Equations. Mr. Chumbley Chemistry 1-2

Chapter 7 Part II: Chemical Formulas and Equations. Mr. Chumbley Chemistry 1-2 Chapter 7 Part II: Chemical Formulas and Equations Mr. Chumbley Chemistry 1-2 SECTION 3: USING CHEMICAL FORMULAS Molecules and Formula Unit We have not yet discussed the different ways in which chemical

More information

Calculating Atoms, Ions, or Molecules Using Moles

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

More information

The Mole. 6.022 x 10 23

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

More information

CHAPTER 7. Empirical Formulas

CHAPTER 7. Empirical Formulas CHAPTER 7 Empirical Formulas Suppose you analyze an unknown compound that is a white powder and find that it is composed of 36.5% sodium, 38.1% oxygen, and 25.4% sulfur. You can use those percentages to

More information

3.4 Molar Mass. Mass of 1 mole C g Mass of 4 mole H g Mass of 1 mole CH g

3.4 Molar Mass. Mass of 1 mole C g Mass of 4 mole H g Mass of 1 mole CH g 3.4 Molar Mass A chemical compound is a collection of atoms. The mass of 1 mole of methane can be found by summing the masses of carbon and hydrogen present: Mass of 1 mole C 12.01 g Mass of 4 mole H 4

More information

3 large lures x 22.0 g/lure + 5 medium lures x 12.9 g/lure + 5 small lures x 8.5 g/lure g packaging = g

3 large lures x 22.0 g/lure + 5 medium lures x 12.9 g/lure + 5 small lures x 8.5 g/lure g packaging = g Answers additional questions 7.1 1. Describe how the particles of sodium bromide, an ionic compound, are different from water, a covalent compound. Give the particle name of each compound type. Ionic compounds

More information

The Mole IT IS JUST A STANDARD NUMBER OF ATOMS/MOLECULES

The Mole IT IS JUST A STANDARD NUMBER OF ATOMS/MOLECULES The Mole S 6.02 X 10 23 IT IS JUST A STANDARD NUMBER OF ATOMS/MOLECULES Relative Masses To understand relative scales, let s s ignore electrons and compare atoms by total number of nuclear particles. Hydrogen,

More information

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 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

More information

Module Three Characterizing Compounds Using Mass Percents and Empirical Formulas. Chem 170. Stoichiometric Calculations.

Module Three Characterizing Compounds Using Mass Percents and Empirical Formulas. Chem 170. Stoichiometric Calculations. Chem 170 Stoichiometric Calculations Module Three Characterizing Compounds Using Mass Percents and Empirical Formulas DePauw University Department of Chemistry and Biochemistry Page 1 Introduction to Module

More information

EXPERIMENT 12: Empirical Formula of a Compound

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

More information

The Mole and Molar Mass

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.

More information

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

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

More information

Percent Composition, Empirical and Molecular Formulas

Percent Composition, Empirical and Molecular Formulas Percent Composition, Empirical and Molecular Formulas Chemists create new compounds for industry, pharmaceutical, and home use Analytical chemist analyzes new compound to provide proof of composition and

More information

Chemical Proportions in Compounds

Chemical Proportions in Compounds Chapter 3 Chemical Proportions in Compounds Note to teacher: You will notice that there are two different formats for the Sample Problems in the student textbook. Where appropriate, the Sample Problem

More information

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 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

More information

Mole - Mass Relationships in Chemical Systems

Mole - Mass Relationships in Chemical Systems Chapter 3: Stoichiometry Mole - Mass Relationships in Chemical Systems 3.1 The Mole 3.2 Determining the Formula of an Unknown Compound 3.3 Writing and Balancing Chemical Equations 3.4 Calculating the Amounts

More information

The Mole Concept and Atoms

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

More information

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

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

More information

Matter. Atomic weight, Molecular weight and Mole

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

More information

Chapter 3: Stoichiometry

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.

More information

7.1 Stoichiometry and Percent Yield

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

More information