Ch.3 - Chemical Reactions and Reaction Stoichiometry

Problem 62b

Chapter 3, Problem 62b

The reaction between potassium superoxide, KO2, and CO2, 4 KO2 + 2 CO2¡2K2CO3 + 3 O2 is used as a source of O2 and absorber of CO2 in selfcontained breathing equipment used by rescue workers. (b) How many grams of KO2 are needed to form 7.50 g of O2?

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Identify the balanced chemical equation: \(4 \text{ KO}_2 + 2 \text{ CO}_2 \rightarrow 2 \text{ K}_2\text{CO}_3 + 3 \text{ O}_2\).

Determine the molar mass of \(\text{O}_2\) and \(\text{KO}_2\) using the periodic table.

Calculate the moles of \(\text{O}_2\) produced from 7.50 g using the formula: \(\text{moles} = \frac{\text{mass}}{\text{molar mass}}\).

Use the stoichiometry of the balanced equation to find the moles of \(\text{KO}_2\) needed. According to the equation, 4 moles of \(\text{KO}_2\) produce 3 moles of \(\text{O}_2\).

Convert the moles of \(\text{KO}_2\) to grams using its molar mass: \(\text{mass} = \text{moles} \times \text{molar mass}\).

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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 calculation of reactants and products in chemical reactions based on the balanced chemical equation. It allows us to determine the relationships between the amounts of substances consumed and produced. In this case, it helps us find the mass of KO2 needed to produce a specific mass of O2 by using the mole ratios from the balanced equation.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is essential for converting between the mass of a substance and the number of moles. For KO2 and O2, knowing their molar masses allows us to calculate how many grams of KO2 are required to yield the desired grams of O2.

Balanced Chemical Equation

A balanced chemical equation represents a chemical reaction with equal numbers of each type of atom on both sides of the equation. It provides the stoichiometric coefficients that indicate the proportions of reactants and products. Understanding the balanced equation for the reaction between KO2 and CO2 is crucial for determining the quantities of each substance involved in the reaction.

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Textbook Question

The reaction between potassium superoxide, KO2, and CO2, 4 KO2 + 2 CO2¡2K2CO3 + 3 O2 is used as a source of O2 and absorber of CO2 in selfcontained breathing equipment used by rescue workers. (a) How many moles of O2 are produced when 0.400 mol of KO2 reacts in this fashion?

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