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General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake 6.1 Equations for Chemical Reactions Chapter 6 Chemical Reactions and Quantities © 2013 Pearson Education, Inc. Lectures
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 2 Chemical Change A chemical change occurs when a substance is converted into one or more new substances. Chemical changes can be recognized by a change in color, the formation of a solid, or the formation of bubbles. A chemical change produces new substances. When silver (Ag) reacts with sulfur (S), it produces silver sulfide (Ag 2 S).
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 3 Evidence of Chemical Change
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 4 Chemical Reactions A chemical reaction involves the rearrangement of atoms. produces one or more new substances. can be observed by the appearance of new physical properties. A chemical reaction forms new products with different properties. An antacid (NaHCO 3 ) tablet in water forms bubbles of carbon dioxide (CO 2 ).
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 5 Writing a Chemical Equation A chemical equation tells us what substances react (reactants) and what substances are formed (products).
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 6 Writing a Chemical Equation Reaction Description: In a Bunsen burner, natural gas (methane, CH 4 ) burns in oxygen, producing carbon dioxide gas and water vapor. Skeleton Equation: Identify the reactants (CH 4 and O 2 ) and products (CO 2 and H 2 O) and write equation: CH 4(g) + O 2(g) CO 2(g) + H 2 O (g)
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 7 Equation for a Chemical Reaction
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 8 Law of Conservation of Mass Fundamental scientific law, first established in the late 1790’s by French chemist Antoine LaVoisier known as the father of modern chemistry LaVoisier showed that the total mass of the reactants in a chemical reaction always equals the total mass of the products “For any chemical reaction, the mass of the reactants always equals the mass of the products” 8
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 9 Balanced Chemical Equations In a balanced chemical equation, the number of atoms in the reactants is equal to the number of atoms in the products for each element.
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 10 Balancing Chemical Equations To balance a chemical equation, whole number coefficients are placed in front of the chemical formulas. coefficients in front of a molecule represent the multiple of that molecule needed in a balanced reaction. subscripts are never changed.
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 11 Checking a Balanced Equation Atoms C11 Atoms H44 Atoms O44 Reactants Products balanced
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 12 Guide to Balancing a Chemical Equation
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 13 Steps to Balancing a Chemical Equation Balance the following chemical reaction: Ethanol (C 2 H 6 O) burns in the presence of oxygen gas(O 2 ) to produce steam (H 2 O) and carbon dioxide (CO 2 ) gas. Step 1 Write an equation using the correct formulas of the reactants and products.
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 14 Steps to Balancing a Chemical Equation Step 2 Count the atoms of each element in the reactants and products. Reactants Products not balanced balanced Atoms of C21 Atoms of H62 Atoms of O33
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 15 Steps to Balancing a Chemical Equation Step 3 Use coefficients to balance each element. Step 4 Check the final equation to confirm it is balanced. Create a balance sheet to count atoms of each element. Reactants Products balanced Atoms of C22 Atoms of H66 Atoms of O77
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 16 Learning Check Determine if each equation is balanced or not.
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 17 Write a balanced equation for the reaction of nitrogen gas (N 2 ) with hydrogen gas (H 2 ) to form ammonia gas (NH 3 ). Learning Check
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 18 Check the balance of atoms in the following equation: 1. number of H atoms in products A. 2B. 4C. 8 2. number of O atoms in reactants A. 2B. 4C. 8 3. number of Fe atoms in reactants A. 1B. 3C. 4 Learning Check
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 19 Equations with Polyatomic Ions When balancing equations with polyatomic ions that remain the same on both sides of the equation, balance them as a unit.
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 20 Balancing with Polyatomic Ions Balance the following chemical equation. Step 1 Write the equation using the correct formulas of the reactants and products.
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 21 Balancing with Polyatomic Ions Balance the following chemical equation. Step 2 Count the atoms of each element in the reactants and products. Reactants Products not balanced Atoms of Na31 PO 4 3− ions12 Atoms of Mg13 Atoms of Cl21
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 22 Balancing with Polyatomic Ions Step 3 Use coefficients to balance each element. Step 4 Check the final equation to confirm it is balanced. Atoms of Na66 PO 4 3− ions22 Atoms of Mg33 Atoms of Cl66 Balance the following chemical equation. ReactantsProducts balanced
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© 2013 Pearson Education, Inc. Chapter 6, Section 1 23 Balance and list the coefficients from reactants to products. 1. __Fe 2 O 3 (s) + __C(s) __Fe(s) + __CO 2 (g) A. 2, 3, 2,3 B. 2, 3, 4, 3 C. 1, 1, 2, 3 2. __Al(s) + __FeO(s) __Fe(s) + __Al 2 O 3 (s) A. 2, 3, 3, 1 B. 2, 1, 1, 1 C. 3, 3, 3, 1 3. __Al(s) + __H 2 SO 4 (aq) __Al 2 (SO 4 ) 3 (aq) + __H 2 (g) A. 3, 2, 1, 2 B. 2, 3, 1, 3 C. 2, 3, 2, 3 Learning Check
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General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake 6.2 Types of Reactions Chapter 6 Chemical Reactions and Quantities © 2013 Pearson Education, Inc. Lectures
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 25 Types of Reactions Chemical reactions can be classified as combination reactions, decomposition reactions, single replacement reactions, double replacement reactions, or combustion reactions.
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 26 Combination Reaction In a combination reaction, two or more elements (or simple compounds) combine to form one product.
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 27 Formation of MgO
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 28 Decomposition Reaction In a decomposition reaction, one substance splits into two or more simpler substances.
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 29 Decomposition of HgO
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 30 Single Replacement Reaction In a single replacement reaction, one element takes the place of a different element in a reacting compound.
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 31 Zn and HCl Combine in a Single Replacement Reaction
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 32 Double Replacement Reaction In a double replacement reaction, the two positive ions in the reacting compounds exchange places.
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 33 Example of Double Replacement
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 34 Combustion Reaction In a combustion reaction, a carbon-containing compound that is the fuel burns in oxygen from the air to produce carbon dioxide (CO 2 ), water (H 2 O), and energy in the form of heat or a flame.
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 35 Combustion Reaction
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 36 Summary Reaction Types
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 37 Learning Check Classify the following reactions as a combination or decomposition reaction.
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 38 Learning Check Classify each of the following reactions as a single replacement or a double replacement reaction.
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© 2013 Pearson Education, Inc. Chapter 6, Section 2 39 Learning Check Identify each of the following reactions as a combination, a decomposition, a single replacement, a double replacement, or a combustion reaction.
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General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake 6.3 Oxidation–Reduction Reactions Chapter 6 Chemical Reactions and Quantities © 2013 Pearson Education, Inc. Lectures
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 41 Everyday Oxidation–Reduction Reactions In an oxidation–reduction reaction, electrons are transferred from one substance to another. if one substance loses electrons, another substance must gain electrons. energy is provided to us from food. electrical energy is provided in batteries. iron rusts.
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 42 In oxidation–reduction reactions, the process of losing electrons is called oxidation. Oxidation Is a Loss of electrons. (OIL) the process of gaining electrons is called reduction. Reduction Is a Gain of electrons. (RIG) Transfer of Electrons
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 43 Oxidation and Reduction
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 44 Oxidized or Reduced?
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 45 Oxidation and Reduction, Formation of CaS In the reaction: the reactant, Ca has a charge of 0 and the product, CaS contains a Ca 2+ ion. calcium loses two electrons, meaning oxidation has taken place. the reactant, S has a charge of 0 and the product, CaS contains an S 2− ion. sulfur gains two electrons, meaning reduction has taken place.
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 46 Oxidation and Reduction, Formation of CaS Adding the two reactions, oxidation and reduction, gives us the overall reaction. The overall reaction is written as:
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 47 Zn and Cu 2+ When zinc is added to copper(II) sulfate, zinc undergoes oxidation, while copper undergoes reduction.
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 48 Electron Transfer from Zn to Cu 2+ Oxidation: electron loss Reduction: electron gain
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 49 Identify each of the following reactions as oxidation or reduction. Learning Check
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 50 Learning Check In light-sensitive sunglasses, UV light initiates an oxidation-reduction reaction. 1. Which reactant is oxidized? 2. Which reactant is reduced?
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 51 Learning Check Identify the substances that are oxidized and reduced in each of the following reactions.
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 52 Oxidation–Reduction in Biological Systems In biological systems, oxidation may involve the loss of H or the gain of O. In biological systems, reduction may involve the gain of H or the loss of O.
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 53 Oxidation–Reduction in Biological Systems
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 54 Characteristics of Oxidation and Reduction
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 55 General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake 6.4 The Mole Chapter 6 Chemical Reactions and Quantities © 2013 Pearson Education, Inc. Lectures
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 56 Counting Units Counting terms are used to describe specific quantities. 1 dozen donuts = 12 donuts 1 ream of paper = 500 sheets 1 case = 24 cans
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 57 A mole is a counting unit that contains the same number of particles as there are carbon atoms in 12.0 g of carbon 12 C. 6.02 x 10 23 atoms of an element (Avogadro’s number). A Mole of Atoms
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 58 1 mole of sulfur contains Avogadro’s number of atoms. A Mole of Sulfur
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 59 A mole of a covalent compound has Avogadro’s number of molecules. of an ionic compound contains Avogadro’s number of formula units. A Mole of a Compound
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 60 Number of Particles in One Mole
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 61 Avogadro’s number (6.02 x 10 23 ) can be written as an equality and two conversion factors. Equality: Conversion Factors: Avogadro’s Number as an Equality
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 62 Guide to Calculating Atoms or Moles
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 63 Using Avogadro’s Number in Calculations How many Cu atoms are in 0.50 mole of Cu? Step 1 State the given and needed quantities. Analyze the Problem. Step 2 Write a plan to convert moles to atoms or molecules. moles of Cu Avogadro's number atoms of Cu GivenNeed 0.50 mole Cuatoms of Cu
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 64 Using Avogadro’s Number in Calculations How many Cu atoms are in 0.50 mole of Cu? Step 3 Use Avogadro’s number to write conversion factors.
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 65 Using Avogadro’s Number in Calculations How many Cu atoms are in 0.50 mole of Cu? Step 4 Set up the problem to calculate the number of particles.
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 66 Learning Check How many moles of CO 2 are in 2.50 x 10 24 molecules of CO 2 ?
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 67 Subscripts State Atoms and Moles
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 68 Moles of Elements in a Formula The subscripts in a formula give the relationship of atoms in the formula and the moles of each element in 1 mole of a compound. Glucose C 6 H 12 O 6
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 69 Conversion Factors from Subscripts Subscripts used for conversion factors relate moles of each element in 1 mole of a compound For aspirin, C 9 H 8 O 4, can be written as:
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 70 Guide to Calculating Moles
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 71 Calculating Moles of an Element How many moles of carbon are present in 2.3 moles of C 5 H 10 O 2, propyl acetate, the compound that provides the odor and taste of pears. Step 1 State the given and needed quantities. Analyze the Problem. GivenNeed 2.3 moles of C 5 H 10 O 2 moles of C
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 72 Calculating Moles of an Element How many moles of carbon are present in 2.3 moles of C 5 H 10 O 2, propyl acetate, the compound that provides the odor and taste of pears. Step 2 Write a plan to convert moles of compound to moles of an element. moles of C 5 H 10 O 2 subscriptmoles of C
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 73 Calculating Moles of an Element How many moles of carbon are present in 2.3 moles of C 5 H 10 O 2, propyl acetate, the compound that provides the odor and taste of pears. Step 3 Write equalities and conversion factors using subscripts.
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 74 Calculating Moles of an Element How many moles of carbon are present in 2.3 moles of C 5 H 10 O 2, propyl acetate, the compound that provides the odor and taste of pears. Step 4 Set up the problem to calculate the moles of an element.
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 75 Learning Check How many O atoms are in 0.150 mole of aspirin, C 9 H 8 O 4 ?
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 76 General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake 6.5 Molar Mass Chapter 6 Chemical Reactions and Quantities © 2013 Pearson Education, Inc. Lectures
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 77 Molar mass is the mass of one mole of a substance. the number of grams that equals the atomic mass of that element. Molar Mass Molar mass is rounded to the tenths (0.1 g) place for use in this text.
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 78 Give the molar mass of the following elements to the nearest 0.1 g. 1. K= ________ 2. Sn= ________ 3. Si= ________ Learning Check
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 79 Guide to Calculating Molar Mass
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 80 Molar Mass of CaCl 2 We calculate the molar mass of CaCl 2 to the nearest 0.1 g as follows. Analyze the Problem. Step 1 Obtain the molar mass of each element. GivenNeed formula unit CaCl 2 molar mass of Ca, Cl; CaCl 2
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 81 Molar Mass of CaCl 2 We calculate the molar mass of CaCl 2 to the nearest 0.1 g as follows. Step 2 Multiply each molar mass by the number of moles (subscript) in the formula. Grams from 1 mole of Ca Grams from 2 moles of Cl
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 82 Molar Mass of CaCl 2 We calculate the molar mass of CaCl 2 to the nearest 0.1 g as follows. Step 3 Calculate the molar mass by adding the masses of the elements.
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 83 Learning Check Determine the molar mass of K 3 PO 4 to 0.1 g.
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 84 Prozac, C 17 H 18 F 3 NO, is an antidepressant that inhibits the uptake of serotonin by the brain. What is the molar mass of Prozac? A. 40.0 g/mole B. 262 g/mole C. 309 g/mole Learning Check
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 85 One-Mole Quantities 32.1 g 55.9 g 58.5 g 294.2 g 342.3 g
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 86 Methane (CH 4 ), known as natural gas, is used in gas stoves and gas heaters. 1 mole of CH 4 = 16.0 g of CH 4 The molar mass of methane can be written as conversion factors Conversion Factors from Molar Mass
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 87 Calculations Using Molar Mass
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 88 How many moles are present in a 65.1 g sample of KCl? Step 1 State the given and needed quantities. Analyze the Problem. Step 2 Write a plan to convert grams to moles. grams of KCl Molar Mass moles of KCl Converting Mass to Moles, KCl GivenNeed 65.1 g of KClmoles of KCl
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 89 How many moles are present in a 65.1 g sample of KCl? Step 3 Determine the molar mass and write conversion factors. Step 4 Set up the problem to convert grams to moles. Converting Mass to Moles, KCl 1 mole of KCl = 74.6 g of KCl
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 90 Acetic acid, C 2 H 4 O 2, gives the sour taste to vinegar. Calculate the moles of acetic acid present in a 25.8 g sample. Learning Check
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 91 Connections between Mass, Moles, and Particles
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© 2013 Pearson Education, Inc. Chapter 6, Section 3 92 Calcium carbonate, CaCO 3 is found in antacid tablets. If we have a 0.320 mole sample of CaCO 3, how many grams are present? Learning Check
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