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Ch.7 - Periodic Properties of the Elements
Chapter 7, Problem 115c

Potassium superoxide, KO2, is often used in oxygen masks (such as those used by firefighters) because KO2 reacts with CO2 to release molecular oxygen. Experiments indicate that 2 mol of KO2(s) react with each mole of CO2(g). (c) What mass of KO2(s) is needed to consume 18.0 g CO2(g)? What mass of O2(g) is produced during this reaction?

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<insert step 1> Determine the molar mass of CO_2 by adding the atomic masses of carbon (C) and oxygen (O). The molar mass of CO_2 is the sum of the atomic mass of C (12.01 g/mol) and two times the atomic mass of O (16.00 g/mol).
<insert step 2> Calculate the number of moles of CO_2 using the given mass (18.0 g) and the molar mass of CO_2. Use the formula: \( \text{moles of CO}_2 = \frac{\text{mass of CO}_2}{\text{molar mass of CO}_2} \).
<insert step 3> Use the stoichiometry of the reaction to find the moles of KO_2 needed. According to the balanced chemical equation, 2 moles of KO_2 react with 1 mole of CO_2. Therefore, multiply the moles of CO_2 by 2 to find the moles of KO_2 required.
<insert step 4> Calculate the mass of KO_2 needed using its molar mass. First, determine the molar mass of KO_2 by adding the atomic masses of potassium (K), oxygen (O), and another oxygen (O). Then, use the formula: \( \text{mass of KO}_2 = \text{moles of KO}_2 \times \text{molar mass of KO}_2 \).
<insert step 5> Determine the mass of O_2 produced. From the stoichiometry of the reaction, find the moles of O_2 produced per mole of CO_2 reacted. Then, calculate the mass of O_2 using its molar mass (32.00 g/mol) and the moles of O_2 produced. Use the formula: \( \text{mass of O}_2 = \text{moles of O}_2 \times \text{molar mass of O}_2 \)."]}

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It allows us to calculate the amounts of substances consumed and produced based on balanced chemical equations. In this case, knowing the stoichiometric ratio between KO2 and CO2 is essential to determine how much KO2 is needed to react with a given mass of CO2.
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Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is crucial for converting between the mass of a substance and the number of moles. To solve the problem, we need to calculate the molar mass of KO2 and CO2 to find out how many grams of KO2 are required to react with 18.0 g of CO2.
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Gas Laws

Gas laws describe the behavior of gases in relation to pressure, volume, temperature, and the number of moles. In this context, understanding how the reaction produces O2 gas is important, as it relates to the ideal gas law and the conditions under which gases are measured. The reaction's stoichiometry will also help determine the amount of O2 produced from the reaction of KO2 with CO2.
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