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

Size: px
Start display at page:

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

Transcription

1 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 on context and viewpoint. Zirconium (at.no. 40) has the symbol Zr. From a microscopic view, the symbol can represent one atom as an independent entity, and/or the mass of one atom, amu. From a macroscopic view, the symbol can represent one mole of atoms, and/or a mass of grams of zirconium. It depends on context. Interpretation of a chemical formula for a molecular compound is likewise interpreted in several ways. Cholesterol has the formula C 27 H 46 O with a molecular weight of 386. From a microscopic view, the formula can represent one molecule, or the number of atoms in one molecule, or refer to the mass of one molecule, 386 amu. From a macroscopic view the formula can represent one mole of molecules as well as a mass of 386 grams of the compound. A balanced chemical equation depicting a chemical reaction is similarly interpreted in several ways. counting, masses and weighing, are equivalent concepts in chemistry; chemists count by weighing. Numbers and Chemical Stoichiometry refers to the application of number / mass content as represented by symbols of elements, formulas of compounds, and chemical equations depicting reactions, and is used to determine quantitative information about chemical substances and chemical processes. It is an omnipresent part of all chemistry, and in CHEM 101/105 the majority of our work involves stoichiometric calculations. 1. Chemical Stoichiometry given a formula for a compound, find its per cent composition. Per cent is often referred to as "part over whole times 100". If the "part" is the amount of a given element in the compound, then the per cent composition of that element in the compound will be "part over whole, times 100". Consider cholesterol: total mass of a cholesterol molecule = 386 amu (the whole) mass of element carbon in cholesterol = (27 carbon atoms)x(12 amu per carbon) = 324 amu (the part) per cent carbon (by weight) in cholesterol = similarly for the other atom-types present in cholesterol: Of course the sum of all percentages add to 100. [ 324 amu C] [ 386 amu cmpd] % H = 46., % O. = = = 414 = % C (part over whole) A. Calcium (Ca) and chlorine (Cl) combine to form a compound. In one reaction g of Ca combined with g of Cl to form g of compound, with some Cl left over. What is the per cent composition of this compound? B. An oxide of mercury was decomposed by Joseph Priestly in a historically important reaction. After g of the oxide was heated, and all of the oxygen driven off, then g of pure mercury remained. What is the per cent composition of the oxide. Correctly name the oxide. C. Benzoic acid is composed of the elements C, H, and O. When a g sample of benzoic acid is burned (i.e., completely combusted in an XS of oxygen gas) all of the carbon is converted to g of carbon dioxide, and all hydrogen is converted to g of water. What is the per cent composition of benzoic acid? Before continuing it will be worthwhile to pause and reflect upon the true meaning of atomic weight values in the periodic table, and their application

2 Note well that atomic masses are RELATIVE MASSES of atoms - all compared to the mass of an atom of carbon-12 (the isotope with 6 protons and 6 neutrons) which is assigned a mass of amu. What could a comparison of Atomic Weights of two elements be called? A ratio? But isn't that a conversion factor? Yes, a conversion factor that shows the relative weights of atoms for two elements. Given that an atom of tellurium (Te, at.no. = 52) has a standard mass of , and that an atom of scandium (Sc, at.no. = 21) has a standard mass of 44.96, compare the relative weights of these two atoms. [ mass of one Te atom].. [ mass of one Sc atom ] = = Conclude that one tellurium atom is times heavier than one scandium atom (or a scandium atom is 1 / or times the mass of a tellurium atom). Now let's change our point of view. Suppose that a quantity of tellurium weighing grams is placed in a beaker. Secondly, suppose that a quantity of scandium weighing grams is placed in a flask. The quantity of tellurium compared to scandium is greater by a factor of [ ] g / g = / 1. What can be concluded about the number of tellurium atoms in the beaker compared to scandium atoms in the flask? (Both contain the same number of atoms.) GRAM quantities of elements or compounds - equal in mass to their standard mass - contain the same number of items. This particular quantity of an element or compound is identified as ONE MOLE of the substance. So: ONE MOLE of all substances contain the SAME NUMBER of items, and ONE MOLE of a chemical substance has a weight (in grams) equal to its standard weight Moles is... (pardon the English) The CONCEPT of moles is comparable to CONCEPTS of percentages and fractions. CONCEPTS of percent and fraction never change. They are always "part over whole". However the VALUES of "part over whole" change depending on the magnitudes of the two items. Thus we meet sales with 10% off, 25 % discount, 1/3 off,... But in every case, it's always "part compared to whole". Similarly, the CONCEPT of moles never changes. It is always "a given mass over the standard mass". However, as noted above, the VALUES of "a given mass over the standard mass" change depending on magnitudes of the given mass and the standard mass of the substance. Thus we meet moles, 2.75 moles, 3.76 x 10-4 moles... But in every case, it's always "a given mass compared to the standard mass". When the part equals the whole then we have 100 %, and the same is true for the fraction of 1 / 1, or in decimal form. Similarly, when the given mass equals the standard mass then we have ONE mole of the substance. However, ONE mole is just a point on a continuum of values. Chemical formulas show ratios of moles of elements present in the compound.

3 An Elemental Symbol, what does it mean? Zr this symbol can represent... from a microscopic view one atom (a number) amu* (mass of one atom) *amu = 10. gram 6. 20x10 23 from a macroscopic view one mole of atoms (a number) grams (mass of a mole of atoms) A Chemical Formula, what does it mean? C 27 H 48 O this symbol can represent... from a microscopic view one molecule (a number) 386 amu* (mass of one molecule) from a macroscopic view one mole of molecules (a number) 386 grams (mass of a mole of molecules)

4 Atomic Weights show relative weights of atoms, all compared to the C-12 isotope. How much heavier / lighter is a* phosphorus atom (has standard mass of amu) magesium atom (has standard mass of amu) weight ratio = or, heavier Why is a phosphorus atom heavier than a magnesium atom? Consider a 50.0 g mass of phosphorus, and a separate 50.0 g mass of magnesium. What can be said about these two quantities. One of these two quantities contains MORE ATOMS than the other. Which substance contains more atoms? How many more atoms does it contain, compared to the other?

5 D. How much heavier is a phosphorus atom when compared to a magnesium atom? (Express this as a ratio, not a difference) Compare standard masses. Phosphorus atom is times heavier than a magnesium atom. mass phosphorus mass magnesium = = E. What mass of silicon will contain the same number of atoms as grams of zinc? The standard mass of zinc = This quantity of zinc (in grams) will contain the same number of atoms as the standard mass of silicon (in grams), which would be grams. So g of Si and g of Zn both contain the same number of atoms. F. What mass of chromium will contain 3.85 times as many atoms as are present in 6.29 grams of boron? Clearly, g chromium and g boron contain the same number of atoms. Use this information to find a similar relation for chromium and 6.29 grams of boron.. g Cr? g Cr = gb g B = g Cr, and then multiply this by 3.85 to get g of chromium. 2. Chemical Stoichiometry determining empirical formulas (based on simplest integer ratio of moles) Reversing the procedure used above to find per cent compositions yields a certain kind of chemical formula. However, it may differ from the actual formula of a molecular compound. It is called an empirical formula. All chemical formulas display ratios of moles of elements present in the compound (as ratios of subscripts), but empirical formulas can only convey the simplest integer ratio of moles of elements. A. Toluene is composed of the elements carbon and hydrogen, and chemical analysis shows a composition of % carbon. What is the empirical formula of toluene? B. An ionic compound is analyzed and found to contain % strontium, % nitrogen, and the remainder is oxygen. What is the empirical formula of the compound? For ionic compounds, the simplest formula is the only formula that can be determined. (Why?) But for molecular compounds, simplest formulas can be some sub-multiple of the molecular formula. The empirical formula could be 1/2, 1/3, 1/4, of the actual molecular formula. To determine a molecular formula requires knowledge of the molecular weight of the compound. Experimental methods for finding molecular weights are few and precious. They represent an important feature in chemistry and we'll note them well in this course. Consider an example of finding an empirical formula, and then proceeding to the molecular formula - when the standard weight is known or given. C. The flavor of oranges is due to a compound composed of elements C, H, and O, and that has a molecular weight of 172 grams / mole. Combustion of g of the compound in xs oxygen yields g of carbon dioxide, and g of water. Determine the empirical formula, and also determine the molecular formula.

6 1. A. Combining weights inform that so many grams of X always combines with so many grams of Y; they are as good an expression of the Law of Constant Composition as is any analytical information. mass Ca = g percent Ca is: mass Cl = mass cmpd - mass Ca = = g what part of the whole is due to Ca? % Ca = / = % percent Cl is: what part of the whole is due to Cl? % Cl = / = % B. mass Hg = g mass O = mass cmpd - mass Hg = = 1.71 g percent Hg is: what part of the whole is due to Hg? % Hg = / = % percent O is: what part of the whole is due to O? C. In a combustion reaction, % O = 1.71 / = 8.00 % all of the carbon present in the original compound is completely converted to carbon dioxide, and all of the hydrogen present in the original compound is completely converted to water. This reaction occurs in the presence of an excess of oxygen gas. Consequently, it is not possible to determine anything about the amount of oxygen that might be present in the original compound g cmpd (C, H, O) --> g CO 2 and g H 2 O In order to find what part of the whole compound is due to carbon, hydrogen, and oxygen (i.e., to determine its composition) first requires finding the carbon present in g of CO 2, the hydrogen present in g of H 2 O, and so on. So, the first question to ask is, what part of carbon dioxide is due to carbon (and so on).? g C = g CO 2? g H = g H 2 O 12 g C 44 g CO 2 2 g H 18 g H2O = g carbon = g hydrogen

7 mass oxygen is obtained by difference:? g O = mass cmpd - ( C + H ) = ( ) = g oxygen The composition of this benzoic acid follows as: % C = / = % % H = / = 5.02 % % O = / = % 2. Chemical formulas show ratios of moles of elements present in the compound, and are of two types; (a) EMPIRICAL FORMULAS show the most simple integer ratio, and (b) MOLECULAR FORMULAS ( the actual formulas for molecular compounds) which are some multiple of the empirical formula. Recall that moles is "a given mass over the standard mass". A. Toluene consists of % carbon and (by difference) 8.70 % hydrogen. Since formulas are ratios of moles, express the given (mass) composition as moles... What part of its standard weight is a given mass of g carbon?? moles C = g 1mole 12 g C = moles carbon What part of its standard weight is a given mass of 8.70 g hydrogen?? moles H = 8.70 g 1 mole H 1 g H = 8.70 moles hydrogen At this point the following formula could be written: C H 8.70 However, an integer ratio of moles is sought, so divide both mole quantities by the smaller value of This results in a formula of... C H Now what? Round off? Absolutely not! Recognize that there are four significant figures in the given information (91.30). Make use of all of them. So find two integers (to FOUR digits) that are related to both and One way of accomplishing this is to set-up a multiplication table involving the two values and a sequential set of integers. In class the use of the EXCEL spreadsheet was demonstrated for finding the two integers.

8 CARBON HYDROGEN x 1 = 2 2 x = x 1 = 3 3 x = x 1 = 4 4 x = x 1 = 5 5 x = x 1 = 6 6 x = x 1 = 7 7 x = x 1 = 8 8 x 1,143 = etc. etc. Conclude that the mole ratio to is the same as the integer ratio of 7 to 8. So the simplest / empirical formula of toluene is: C 7 H 8 The molecular formula cannot be determined from information available in this problem. However, the molecular formula of toluene would be some integer multiple (1, 2, 3...) of this empirical formula. 2. B. mass percents are given: Sr = g N = g O = g A chemical formula shows the ratio of moles of elements present in the compound. Express these masses as mole quantities... 1 mole Sr? moles Sr = g Sr g Sr 1 molen? moles N = g N 14 g N? moles O = g O 1 mole O 16 g O For starters, express the formula as: = moles Sr = moles N = moles O Sr N O divide all by to yield: Sr N 2 O 4 2. C. Combustion is the chemical reaction of a substance with molecular oxygen. In this case the molecular weight is given so the molecular formula can be determined. In addition, a balanced equation will be written for the combustion reaction after determination of the molecular formula. Given: g (C, H, O) forms g CO 2 and g H 2 O Note that the original compound contains oxygen, AND oxygen is also a reactant here. Because there are two sources of oxygen it is not possible to determine the mass of oxygen directly. It must be found indirectly, by first finding masses of carbon and hydrogen present in CO 2 and H 2 O, and then find the mass they (C and H) do not account for in the original compound.

9 ? g C = g CO 2? g H = g H 2 O 12 g C 44 g CO 2 2 g H 18 g H2O = g carbon = g hydrogen mass oxygen is obtained by adding mass C and H, and then subtracting from mass of the original compound:? g O = mass cmpd - ( C + H ) = ( ) = g oxygen Chemical formulas show ratios of moles of elements in compounds. So express these masses as moles...? moles C = g C 1 mole C 12 g C = moles C? moles H = g H 1 mole H 1 g H = moles C? mole O = g O 1 mole O 16 g O = moles O The initial formula can be written as: C H O Dividing by the smaller moles value (0.0248) yields the formula: C 5.00 H O 1.00 Which can be reasonably rounded off to integer values: C 5 H 10 O 1 The sum of standard weights in this empirical formula (i.e., the empirical formula weight ) is: 5 x x x 16 = 86. Recall that the molecular weight was givan as 172 g/mole. Clearly the molecular weight is TWICE the empirical weight, so the actual molecule must have TWICE the number of atoms as are present in the empirical formula. Thus the molecular formula is: C 10 H 20 O 2 (having a MW = 172 g / mole) and the balanced chemical equation for this combustion reaction would be... C 10 H 20 O 2 (s) + 14 O 2 (g) = 10 CO 2 (g) + 10 H 2 O (g)

Chem 115 POGIL Worksheet - Week 4 Moles & Stoichiometry

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

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

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

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 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

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

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

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

More information

Chem 115 POGIL Worksheet - Week 4 Moles & Stoichiometry Answers

Chem 115 POGIL Worksheet - Week 4 Moles & Stoichiometry Answers Key Questions & Exercises Chem 115 POGIL Worksheet - Week 4 Moles & Stoichiometry Answers 1. The atomic weight of carbon is 12.0107 u, so a mole of carbon has a mass of 12.0107 g. Why doesn t a mole of

More information

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. 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

More information

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

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

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

Chapter 8 How to Do Chemical Calculations

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

More information

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 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

More information

KEY for Unit 1 Your Chemical Toolbox: Scientific Concepts, Fundamentals of Typical Calculations, the Atom and Much More

KEY for Unit 1 Your Chemical Toolbox: Scientific Concepts, Fundamentals of Typical Calculations, the Atom and Much More KEY for Unit 1 Your Chemical Toolbox: Scientific Concepts, Fundamentals of Typical Calculations, the Atom and Much More The Modern Periodic Table The Periodic Law - when elements are arranged according

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

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

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

More information

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.

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

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

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

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

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

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

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

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

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

More information

The Empirical Formula of a Compound

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,

More information

Chemical Calculations: Formula Masses, Moles, and Chemical Equations

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

More information

CHEM 105 HOUR EXAM III 28-OCT-99. = -163 kj/mole determine H f 0 for Ni(CO) 4 (g) = -260 kj/mole determine H f 0 for Cr(CO) 6 (g)

CHEM 105 HOUR EXAM III 28-OCT-99. = -163 kj/mole determine H f 0 for Ni(CO) 4 (g) = -260 kj/mole determine H f 0 for Cr(CO) 6 (g) CHEM 15 HOUR EXAM III 28-OCT-99 NAME (please print) 1. a. given: Ni (s) + 4 CO (g) = Ni(CO) 4 (g) H Rxn = -163 k/mole determine H f for Ni(CO) 4 (g) b. given: Cr (s) + 6 CO (g) = Cr(CO) 6 (g) H Rxn = -26

More information

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

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?

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

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

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 1 The Atomic Nature of Matter

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.

More information

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

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

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

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

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

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: 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

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

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

More information

Stoichiometry. Lecture Examples Answer Key

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

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

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

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

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

MOLES AND MOLE CALCULATIONS

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

More information

Unit 6 The Mole Concept

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

More information

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: 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

More information

Formulae, stoichiometry and the mole concept

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

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

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

Problem Solving. Empirical Formulas

Problem Solving. Empirical Formulas Skills Worksheet Problem Solving 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

More information

SYMBOLS, FORMULAS AND MOLAR MASSES

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

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

Chemistry B11 Chapter 4 Chemical reactions

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

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

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 Review

Stoichiometry Review Stoichiometry Review There are 20 problems in this review set. Answers, including problem set-up, can be found in the second half of this document. 1. N 2 (g) + 3H 2 (g) --------> 2NH 3 (g) a. nitrogen

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

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

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 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

More information

2014 Spring CHEM101 Ch1-2 Review Worksheet Modified by Dr. Cheng-Yu Lai,

2014 Spring CHEM101 Ch1-2 Review Worksheet Modified by Dr. Cheng-Yu Lai, Ch1 1) Which of the following underlined items is not an intensive property? A) A chemical reaction requires 3.00 g of oxygen. B) The density of helium at 25 C is 1.64 10-4 g/cm3. C) The melting point

More information

Word Equations and Balancing Equations. Video Notes

Word Equations and Balancing Equations. Video Notes Word Equations and Balancing Equations Video Notes In this lesson, you will: Use the law of conservation of mass and provide standard rules for writing and balancing equations. Write and balance equations

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

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

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

More information

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

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

More information

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: 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

More information

neutrons are present?

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

More information

THE MOLE / COUNTING IN CHEMISTRY

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

More information

CHEMICAL FORMULAS AND FORMULA WEIGHT CALCULATIONS

CHEMICAL FORMULAS AND FORMULA WEIGHT CALCULATIONS CHEMICAL FORMULAS AND FORMULA WEIGHT CALCULATIONS 1. THE MEANING OF A CHEMICAL FORMULA A chemical formula is a shorthand method of representing the elements in a compound. The formula shows the formulas

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

Unit 2: Quantities in Chemistry

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

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

Chemistry Diagnostic Questions

Chemistry Diagnostic Questions Chemistry Diagnostic Questions Answer these 40 multiple choice questions and then check your answers, located at the end of this document. If you correctly answered less than 25 questions, you need to

More information

Chapter 3 Stoichiometry

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

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

Chemical Equations & Stoichiometry

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

More information

20.2 Chemical Equations

20.2 Chemical Equations All of the chemical changes you observed in the last Investigation were the result of chemical reactions. A chemical reaction involves a rearrangement of atoms in one or more reactants to form one or more

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. 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

Name Date Class STOICHIOMETRY. SECTION 12.1 THE ARITHMETIC OF EQUATIONS (pages 353 358)

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.

More information

What s in a Mole? Molar Mass

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

More information

Chemistry Post-Enrolment Worksheet

Chemistry Post-Enrolment Worksheet Name: Chemistry Post-Enrolment Worksheet The purpose of this worksheet is to get you to recap some of the fundamental concepts that you studied at GCSE and introduce some of the concepts that will be part

More information

CONSERVATION OF MASS During a chemical reaction, matter is neither created nor destroyed. - i. e. the number of atoms of each element remains constant

CONSERVATION OF MASS During a chemical reaction, matter is neither created nor destroyed. - i. e. the number of atoms of each element remains constant 1 CHEMICAL REACTINS Example: Hydrogen + xygen Water H + H + + - Note there is not enough hydrogen to react with oxygen - It is necessary to balance equation. reactants products + H + H (balanced equation)

More information

11-1 Stoichiometry. Represents

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

More information

MOLECULAR WEIGHT CALCULATIONS

MOLECULAR WEIGHT CALCULATIONS MOLECULAR WEIGHT CALCULATIONS Calculating Formula Weight; Significant Figures Page 2 Percentage Composition of a Compound 18 Exponential Notation; Avogadro s Number; Moles 28 Calculating Empirical Formulas

More information

Calculations with Chemical Formulas and Equations

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

More information

APPENDIX B: EXERCISES

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

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

Return to Lab Menu. Stoichiometry Exploring the Reaction between Baking Soda and Vinegar

Return to Lab Menu. Stoichiometry Exploring the Reaction between Baking Soda and Vinegar Return to Lab Menu Stoichiometry Exploring the Reaction between Baking Soda and Vinegar Objectives -to observe and measure mass loss in a gas forming reaction -to calculate CO 2 loss and correlate to a

More information

TOPIC 7. CHEMICAL CALCULATIONS I - atomic and formula weights.

TOPIC 7. CHEMICAL CALCULATIONS I - atomic and formula weights. TOPIC 7. CHEMICAL CALCULATIONS I - atomic and formula weights. Atomic structure revisited. In Topic 2, atoms were described as ranging from the simplest atom, H, containing a single proton and usually

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

Description of the Mole Concept:

Description of the Mole Concept: Description of the Mole Concept: Suppose you were sent into the store to buy 36 eggs. When you picked them up you would get 3 boxes, each containing 12 eggs. You just used a mathematical device, called

More information

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

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

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

Introduction to Chemistry

Introduction to Chemistry 1 Copyright ç 1996 Richard Hochstim. All rights reserved. Terms of use. Introduction to Chemistry In Chemistry the word weight is commonly used in place of the more proper term mass. 1.1 Atoms, Ions, and

More information

Stoichiometry. Unit Outline

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

More information

Chapter 3 Mass Relationships in Chemical Reactions

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

More information

Chapter 6 Notes. Chemical Composition

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

More information

IB Chemistry. DP Chemistry Review

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

More information

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

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

More information