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12.2 Chemical Calculations • The effectiveness of car’s air bags is based on the rapid conversion of a small mass of sodium azide into a large volume of gas. The entire reaction occurs in less than a second. You will learn how to use a balanced chemical equation to calculate the amount of product formed in a chemical reaction.
12.2 Writing and Using Mole Ratios • Writing and Using Mole Ratios • How are mole ratios used in chemical calculations?
12.2 Writing and Using Mole Ratios • In chemical calculations, mole ratios are used to convert between moles of reactant and moles of product, between moles of reactants, or between moles of products.
12.2 Writing and Using Mole Ratios • Mole-Mole Calculations • A mole ratio is a conversion factor derived from the coefficients of a balanced chemical equation interpreted in terms of moles.
12.2 Writing and Using Mole Ratios • To determine the number of moles in a sample of a compound, first measure the mass of the sample. Then use the molar mass to calculate the number of moles in that mass.
for Sample Problem 12.2 Problem Solving 12.12 Solve Problem 12 with the help of an interactive guided tutorial.
12.2 Writing and Using Mole Ratios • Mass-Mass Calculations
for Sample Problem 12.3 ` Problem Solving 12.13 Solve Problem 13 with the help of an interactive guided tutorial.
12.2 Other Stoichiometric Calculations • Other Stoichiometric Calculations • What is the general procedure for solving a stoichiometric problem?
12.2 Other Stoichiometric Calculations • In a typical stoichiometric problem, the given quantity is first converted to moles. Then the mole ratio from the balanced equation is used to calculate the number of moles of the wanted substance. Finally, the moles are converted to any other unit of measurement related to the unit mole, as the problem requires.
12.2 Other Stoichiometric Calculations • Solution Diagram
12.2 Other Stoichiometric Calculations • Problem-Solving Approach
Other Stoichiometric Calculations • Simulation 13 • Strengthen your analytical skills by solving stoichiometric problems.
for Sample Problem 12.4 Problem Solving 12.15 Solve Problem 15 with the help of an interactive guided tutorial.
for Sample Problem 12.5 Problem Solving 12.18 Solve Problem 18 with the help of an interactive guided tutorial.
for Sample Problem 12.5 Problem-Solving 12.19 Solve Problem 19 with the help of an interactive guided tutorial.
12.2 Section Quiz. • 12.2.
12.2 Section Quiz. • 1. How many moles of water are produced when 2.5 mol of O2 react according to the following equation? • C3H8 + 5O2 3CO2 + 4H2O • 2.0 • 2.5 • 3.0 • 4.0
12.2 Section Quiz • 2. Nitrogen gas reacts with hydrogen gas to produce ammonia gas. N2(g) + 3H2(g) 2NH3(g) What volume of H2 is required to react with 3.00 L of N2, and what volume of NH3 is produced at 200°C? • volume of H2 = 9.00 L, volume of NH3 = 6.00 L • volume of H2 = 3.00 L, volume of NH3 = 3.00 L • volume of H2 = 3.00 L, volume of NH3 = 6.00 L • volume of H2 = 1.00 L, volume of NH3 = 1.50 L
12.2 Section Quiz • 3. Automotive airbags inflate when sodium azide, NaN3, rapidly decomposes to its component elements via this reaction: 2NaN3 2Na + 3N2. How many grams of sodium azide are required to form 5.00 g of nitrogen gas? • 11.61 g • 17.41 g • 7.74 g • 1.36 g
