1 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 the following elements: (a) Copper (c) sulfur (b) Mercury (d) helium The atomic mass of each element is listed below the symbol of the element in the periodic table: Cu = amu, Hg = amu, S = amu, and He = 4.00 amu. The mass of Avogadro s number of atoms is the atomic mass expressed in grams. Therefore, atoms of (a) Cu = g (c) S = g (b) Hg = g (d) He = 4.00 g Refer to the periodic table and state the mass for each of the following: (a) 1 atom of Au (b) atoms of Au Answers: (a) amu; (b) g What is the mass of an average platinum atom? What is the mass of Avogadro s number of Pt atoms?
2 Example Exercise 9.2 Mole Calculations I Calculate the number of sodium atoms in mol Na. Strategy Plan Step 1: What unit is asked for in the answer? Step 2: What given value is related to the answer? Step 3: What unit factor(s) should we apply? Since 1 mol Na = atoms Na, the two unit factors are 1 mol Na/ atoms Na, and its reciprocal atoms Na/1 mol Na. Unit Analysis Map
3 Example Exercise 9.2 Continued Mole Calculations I We apply the unit factor atoms Na/1 mol Na to cancel moles denominator., which appears in the The answer is rounded to three digits because the given value and unit factor each have three significant digits. Calculate the number of formula units in mol of sodium chloride, NaCl. Answers: formula units NaCl What is the number of molecules in 1.00 mol of any gas?
4 Example Exercise 9.3 Mole Calculations I Calculate the number of moles of potassium in atoms K. Strategy Plan Step 1: What unit is asked for in the answer? Step 2: What given value is related to the answer? Step 3: What unit factor(s) should we apply? Since mol K = atoms K, the two unit factors are 1 mol K/ atoms K, and its reciprocal atoms K/1 mol K. Unit Analysis Map
5 Example Exercise 9.3 Continued Mole Calculations I We apply the unit factor 1 mol K/ atoms K to cancel atoms denominator., which appears in the The answer is rounded to three digits because the given value and unit factor each have three significant digits. Calculate the number of moles of potassium iodide in formula units of KI. Answer: 88.7 mol KI What is the number of molecules in 1.00 mol of iodine crystals?
6 Example Exercise 9.4 Molar Mass Calculations Calculate the molar mass for each of the following substances: (a) silver metal, Ag (b) ammonia gas, NH 3 (c) magnesium nitrate, Mg(NO 3 ) 2 We begin by finding the atomic mass of each element in the periodic table. The molar mass equals the sum of the atomic masses expressed in g/mol. (a) The atomic mass of Ag is amu, and the molar mass of silver equals g/mol. (b) The sum of the atomic masses for NH 3 is amu + 3(1.01)amu = amu. The molar mass of ammonia equals g/mol. (c) The sum of the atomic masses for Mg(NO 3 ) 2 is amu + 2( )amu = amu. The molar mass of magnesium nitrate equals g/mol. Calculate the molar mass for each of the following substances: (a) manganese metal, Mn (b) sulfur hexafluoride, SF 6 (c) strontium acetate, Sr(C 2 H 3 O 2 ) 2 Answers: (a) g/mol; (b) g/mol; (c) g/mol The molecular mass of water is amu. What is the mass of Avogadro s number of water molecules?
7 Example Exercise 9.5 Mole Calculations II What is the mass in grams of atoms of sulfur? Strategy Plan Step 1: What unit is asked for in the answer? Step 2: What given value is related to the answer? Step 3: What unit factor(s) should we apply? By definition, 1 mol S = atoms S, and the molar mass from the periodic table is g S = 1 mol S; the two pairs of unit factors are shown in Step 3. Unit Analysis Map
8 Example Exercise 9.5 Continued Mole Calculations II We apply the unit factor 1 mol S/ atoms S to cancel atoms S cancel mol S :, and g S/1 mol S to What is the mass of formula units of lead(ii) sulfide, PbS? Answer: 30.8 g PbS Sulfur occurs naturally as S 8 molecules. What is the mass of Avogadro s number of S 8 molecules?
9 Example Exercise 9.6 Mole Calculations II How many O 2 molecules are present in g of oxygen gas? Strategy Plan Step 1: What unit is asked for in the answer? Step 2: What given value is related to the answer? Step 3: What unit factor(s) should we apply? The molar mass from the periodic table is g O 2 = 1 mol O 2, and by definition, 1 mol O 2 = molecules O 2. Thus, the two pairs of unit factors are shown in Step 3. Unit Analysis Map
10 Example Exercise 9.6 Continued Mole Calculations II We apply the unit factor 1 mol O 2 /32.00 g O 2 to cancel g O 2 cancel moles O 2. Thus,, and molecules O 2 /1 mol O 2 to How many formula units of lithium fluoride are found in g LiF? Answer: formula units LiF Ozone occurs naturally as O 3 molecules. What is the mass of Avogadro s number of ozone molecules?
11 Example Exercise 9.7 Mass of a Molecule Calculate the mass in grams for a single molecule of carbon dioxide, CO 2 (given that MM = g/mol). Strategy Plan Step 1: What unit is asked for in the answer? Step 2: What given value is related to the answer? Step 3: What unit factor(s) should we apply? By definition, 1 mol CO 2 = molecules. Thus, the unit factors are shown in Step 3. Unit Analysis Map
12 Example Exercise 9.7 Continued Mass of a Molecule We apply the unit factor 1 mol CO 2 / molecules CO 2 to cancel mol CO 2. Calculate the mass in grams for a single molecule of carbon monoxide, CO. Answer: g/molecule What is the mass of a carbon monoxide molecule expressed in amu?
13 Example Exercise 9.8 Density of a Gas at STP Calculate the density of ammonia gas, NH 3, at STP. (MM = g/mol) Strategy Plan Step 1: What unit is asked for in the answer? Step 2: What given value is related to the answer? Step 3: What unit factor(s) should we apply? From the molar volume of a gas at STP, 1 mol = 22.4 L; thus, the unit factors are 1 mol/22.4 L, and 22.4 L/1 mol. Unit Analysis Map
14 Example Exercise 9.8 Continued Density of a Gas at STP We apply the unit factor 1 mol /22.4 L to cancel moles the denominator., which appears in If we filled a balloon with ammonia gas (0.761 g/l), the balloon would float in air (1.29 g/l). Similarly, a less dense liquid floats on a more dense liquid; for example, gasoline (0.7 g/ml) floats on water (1.0 g/ml). Calculate the density of hydrogen sulfide gas, H 2 S, at STP. Answer: 1.52 g/l Why does the balloon filled with helium gas rise, while the balloon filled with nitrogen gas does not?
15 Example Exercise 9.9 Molar Mass of a Gas A fire extinguisher releases 1.96 g of an unknown gas that occupies 1.00 L at STP. What is the molar mass (g/mol) of the unknown gas? Strategy Plan Step 1: What unit is asked for in the answer? Step 2: What given value is related to the answer? Step 3: What unit factor(s) should we apply? From the molar volume of a gas at STP, 1 mol = 22.4 L; thus, the unit factors are 1 mol/22.4 L, and 22.4 L/1 mol. Unit Analysis Map
16 Example Exercise 9.9 Continued Molar Mass of a Gas We apply the unit factor 1 mol/22.4 L to cancel liters, which appears in the denominator. Because the unknown gas is from a fire extinguisher, we suspect that it is carbon dioxide. By summing the molar mass for CO 2 (44.01 g/mol), we help confirm that the unknown gas is carbon dioxide. Boron trifluoride gas is used in the manufacture of computer chips. Given that g of the gas occupies 497 ml at STP, what is the molar mass of boron fluoride gas? Answer: 67.8 g/mol What is the volume of one mole of any gas at STP?
17 Example Exercise 9.10 Mole Calculations III What is the mass of 3.36 L of ozone gas, O3, at STP? Strategy Plan Step 1: What unit is asked for in the answer? Step 2: What given value is related to the answer? Step 3: What unit factor(s) should we apply? From the molar volume of a gas at STP, 1 mol O 3 = 22.4 L O 3. The molar mass from the periodic table is g O 3 = 1 mol O 3. Thus, the two pairs of unit factors are shown in Step 3. Unit Analysis Map
18 Example Exercise 9.10 Mole Calculations III Continued We apply the unit factor 1 mol O 3 /22.4 L O 3 to cancel L O 3 cancel moles O 3,, and g O 3 /1 mol O 3 to What volume is occupied by g of methane gas, CH 4, at STP? Answer: L CH 4 (174 ml) How many molecules of ozone are in one mole of gas?
19 Example Exercise 9.11 Mole Calculations III How many molecules of hydrogen gas, H 2, occupy L at STP? Strategy Plan Step 1: What unit is asked for in the answer? Step 2: What given value is related to the answer? Step 3: What unit factor(s) should we apply? From the molar volume of a gas at STP, 1 mol H 2 = 22.4 L H 2 and by definition, 1 mol H 2 = molecules H 2. Thus, the two pairs of unit factors are shown in Step 3. Unit Analysis Map
20 Example Exercise 9.11 Continued Mole Calculations III We apply the unit factor 1 mol H 2 /22.4 L H 2 to cancel L H 2, and molecules H 2 /1 mol H 2 to cancel moles 77H 2. Thus, What is the volume occupied by atoms of helium gas, He, at STP? Answer: L He (124 ml) What is the mass of one mole of hydrogen gas?
21 Example Exercise 9.12 Percent Composition of a Substance TNT (trinitrotoluene) is a white crystalline substance that explodes at 240 C. Calculate the percent composition of TNT, C 7 H 5 (NO 2 ) 3. Let s calculate the percent composition assuming there is 1 mol of TNT. For compounds with parentheses, it is necessary to count the number of atoms of each element carefully. That is, 1 mol of C 7 H 5 (NO 2 ) 3 contains 7 mol of C atoms, 5 mol of H atoms, 3 mol of NO 2 (that is, 3 mol N atoms and 6 mol of O atoms). We begin the calculation by finding the molar mass of C 7 H 5 (NO 2 ) 3 as follows: Now, let s compare the mass of each element to the total molar mass of the compound, that is, g. The percent composition of TNT reveals that the explosive is mostly oxygen by mass. When we sum the individual percentages ( = 99.99%), we verify our calculation and, find that the total is approximately 100%.
22 Example Exercise 9.12 Continued Percent Composition of a Substance EDTA (ethylenediaminetetraacetic acid) is used as a food preservative and in the treatment of metallic lead poisoning. Calculate the percent composition of EDTA, C 10 H 16 N 2 O 8. Answers: 41.09% C, 5.53% H, 9.587% N, and 43.79% O If an analysis of sugar, C x H y O z, gave 40.0% C and 6.7% H, what is the percent oxygen? Answers: See Appendix G.
23 Example Exercise 9.13 Empirical Formula from Mass Composition In a laboratory experiment, g of scandium was heated and allowed to react with oxygen from the air. The resulting product oxide had a mass of g. Now, let s find the empirical formula for scandium oxide, Sc? O?. The empirical formula is the simplest whole-number ratio of scandium and oxygen in the compound scandium oxide. This ratio is experimentally determined from the moles of each reactant. The moles of scandium are calculated as follows: The moles of oxygen are calculated after first subtracting the mass of Sc from the product, Sc? O? : The moles of oxygen are calculated from the mass of oxygen that reacted: The mole ratio in scandium oxide is Sc O To simplify the ratio and obtain small whole numbers, we divide by the smaller number: Since the calculated ratio is not close to whole numbers, we cannot round off the experimental ratio Sc 1.00 O However, we can double the ratio to obtain whole numbers, that is, Sc 2.00 O Thus, the empirical formula is Sc 2 O 3.
24 Example Exercise 9.13 Continued Empirical Formula from Mass Composition Iron can react with chlorine gas to give two different compounds, FeCl 2 and FeCl 3. If g of metallic iron reacts with chlorine gas to yield g of iron chloride, which iron compound is produced in the experiment? Answer: FeCl 3 If mol of yellow powder sulfur reacts with mol of oxygen gas, what is the empirical formula of the sulfur oxide?
25 Example Exercise 9.14 Empirical Formula from Percent Composition Glycine is an amino acid found in protein. An analysis of glycine gave the following data: 32.0% carbon, 6.7% hydrogen, 18.7% nitrogen, and 42.6% oxygen. Calculate the empirical formula of the amino acid. If we assume a 100 g sample, then the percentage of each element equals its mass in 100 g of glycine, that is, 32.0 g C, 6.7 g H, 18.7 g N, and 42.6 g O. We can determine the empirical formula as follows: The mole ratio of the elements in the amino acid is C 2.66 H 6.6 N 1.33 O We can find a small whole-number ratio by dividing by the smallest number: Simplifying, we find that the empirical formula for the amino acid glycine is C 2 H 5 NO 2.
26 Example Exercise 9.14 Continued Empirical Formula from Percent Composition Calculate the empirical formula for caffeine given the following percent composition: 49.5% C, 5.15% H, 28.9% N, and 16.5% O. Answer: C 4 H 5 N 2 O If mol of yellow powder sulfur reacts with mol of oxygen gas, what is the empirical formula of the sulfur oxide?
27 Example Exercise 9.15 Molecular Formula from Empirical Formula The empirical formula for fructose, or fruit sugar, is CH 2 O. If the molar mass of fructose is 180 g/mol, find the actual molecular formula for the sugar. We can indicate the molecular formula of fructose as (CH2O)n. The molar mass of the empirical formula CH 2 O is 12 g C + 2(1 g H) + 16 g O = 30 g/mol. Thus, the number of multiples of the empirical formula is Thus, the molecular formula of fructose is (CH 2 O) 6 or C 6 H 12 O 6. Ethylene dibromide was used as a grain pesticide until it was banned. Calculate (a) the empirical formula and (b) the molecular formula for ethylene dibromide given its approximate molar mass of 190 g/mol and its percent composition: 12.7% C, 2.1% H, and 85.1% Br. Answers: (a) CH 2 Br; (b) C 2 H 4 Br 2 If the molecular formula of hydrogen peroxide is H 2 O 2, what is the empirical formula?
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
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
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
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
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
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
Pre- AP Chemistry Chemical Quan44es: The Mole Mole SI unit of measurement that measures the amount of substance. A substance exists as representa9ve par9cles. Representa9ve par9cles can be atoms, molecules,
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
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
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
Unit 9 Stoichiometry Notes (The Mole Continues) is a big word for a process that chemist s use to calculate amounts in reactions. It makes use of the coefficient ratio set up by balanced reaction equations
Moles, Molecules, and Grams Worksheet Answer Key 1) How many are there in 24 grams of FeF 3? 1.28 x 10 23 2) How many are there in 450 grams of Na 2 SO 4? 1.91 x 10 24 3) How many grams are there in 2.3
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
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?
Lecture 5, The Mole What is a mole? Moles Atomic mass unit and the mole amu definition: 12 C = 12 amu. The atomic mass unit is defined this way. 1 amu = 1.6605 x 10-24 g How many 12 C atoms weigh 12 g?
Chapter 3 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
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.
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.
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
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
Atomic mass: p + = protons; e - = electrons; n 0 = neutrons p + + n 0 = atomic mass o For carbon-12, 6p + + 6n 0 = atomic mass of 12.0 o For chlorine-35, 17p + + 18n 0 = atomic mass of 35.0 atomic mass
Chapter 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
Woods Chem-1 Lec-02 10-1 Atoms, Ions, Mole (std) Page 1 ATOMIC THEORY, MOLECULES, & IONS Proton: A positively charged particle in the nucleus Atomic Number: We differentiate all elements by their number
Moles Balanced chemical equations Molar ratios Mass Composition Empirical and Molecular Mass Predicting Quantities Equations Micro World atoms & molecules Macro World grams Atomic mass is the mass of an
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!
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
Unit 9 Compounds Molecules INTRODUCTION Compounds are the results of combinations of elements. These new substances have unique properties compared to the elements that make them up. Compounds are by far
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
Stoichiometry 1 The total number of moles represented by 20 grams of calcium carbonate is (1) 1; (2) 2; (3) 01; (4) 02 2 A 44 gram sample of a hydrate was heated until the water of hydration was driven
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
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
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
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
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.
1. How many iron atoms are present in one mole of iron? Ans. 6.02 1023 atoms 2. How many grams of sulfur are found in 0.150 mol of sulfur? [Use atomic weight: S, 32.06 amu] Ans. 4.81 g 3. How many moles
MASS RELATIONSHIPS IN CHEMICAL REACTIONS 1. The mole, Avogadro s number and molar mass of an element. Molecular mass (molecular weight) 3. Percent composition of compounds 4. Empirical and Molecular formulas
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
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.
Chapter 3 ATOMS AND MOLECULES Multiple Choice Questions 1. Which of the following correctly represents 360 g of water? (i) 2 moles of H 2 0 (ii) 20 moles of water (iii) 6.022 10 23 molecules of water (iv)
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
Skills Worksheet Problem Solving Percentage Composition Suppose you are working in an industrial laboratory. Your supervisor gives you a bottle containing a white crystalline compound and asks you to determine
HOMEWORK 4A Oxidation-Reduction Reactions 1. Indicate whether a reaction will occur or not in each of following. Wtiring a balcnced equation is not necessary. (a) Magnesium metal is added to hydrochloric
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
3 Formulae, stoichiometry and the mole concept Content 3.1 Symbols, Formulae and Chemical equations 3.2 Concept of Relative Mass 3.3 Mole Concept and Stoichiometry Learning Outcomes Candidates should be
Chapter 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
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
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
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
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
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
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
Skills Worksheet Problem Solving Mole Concept Suppose you want to carry out a reaction that requires combining one atom of iron with one atom of sulfur. How much iron should you use? How much sulfur? When
HOMEWORK 5A Barometer; Boyle s Law 1. The pressure of the first two gases below is determined with a manometer that is filled with mercury (density = 13.6 g/ml). The pressure of the last two gases below
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
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
44 Section 43 Questions 1 Define Avogadro s constant, and explain its significance in quantitative analysis 2 Distinguish between the terms atomic mass and molar mass 3 Calculate the mass of a molecule
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
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
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
Micro World atoms & molecules Laboratory scale measurements Atomic mass is the mass of an atom in atomic mass units (amu) By definition: 1 atom 12 C weighs 12 amu On this scale 1 H = 1.008 amu 16 O = 16.00
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
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
Skills Worksheet Problem Solving Stoichiometry of Gases Now that you have worked with relationships among moles, mass, and volumes of gases, you can easily put these to work in stoichiometry calculations.
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
CHAPTER 8 1. 100 washers 0.110 g 1 washer 100. g 1 washer 0.110 g = 11.0 g (assuming 100 washers is exact). = 909 washers 2. The empirical formula is CFH from the structure given. The empirical formula
Stoichiometry 1 The total number of moles represented by 20 grams of calcium carbonate is (1) 1; (2) 2; (3) 01; (4) 02 2 A 44 gram sample of a hydrate was heated until the water of hydration was driven
Chemical Equations & Stoichiometry Chapter Goals Balance equations for simple chemical reactions. Perform stoichiometry calculations using balanced chemical equations. Understand the meaning of the term
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
A dozen Molar Mass Science 10 is a number of objects. A dozen eggs, a dozen cars, and a dozen people are all 12 objects. But a dozen cars has a much greater mass than a dozen eggs because the mass of each
9.1 Naming Ions I. Monatomic Ions A. Monatomic ions 1. Ions formed from a single atom Unit 4 Conservation of Mass and Stoichiometry B. Naming Monatomic Ions 1. Monatomic cations are a. Identified by the
Mole Concept Multiple Choice questions (one answer correct) (1) Avogadro s number represents the number of atoms in (a) 12g of C 12 (b) 320g of sulphur (c) 32g of oxygen (d) 12.7g of iodine (2) The number
Instructions for Conversion Problems For every conversion problem Write the number in the problem down with unit and a multiplication sign Decide which conversion factor you should use, Avagadro s or molar