Ch.3 - Chemical Reactions and Reaction Stoichiometry

Problem 99b

Chapter 3, Problem 99b

A method used by the U.S. Environmental Protection Agency (EPA) for determining the concentration of ozone in air is to pass the air sample through a 'bubbler' containing sodium iodide, which removes the ozone according to the following equation: O31g2 + 2 NaI1aq2 + H2O1l2¡ O21g2 + I21s2 + 2 NaOH1aq2 (b) How many grams of sodium iodide are needed to remove 1.3 mg of O3?

Verified step by step guidance

Step 1: Convert the mass of ozone from milligrams to grams. This is done by dividing the given mass by 1000, since there are 1000 milligrams in a gram.

Step 2: Calculate the number of moles of ozone. This is done by dividing the mass of ozone (in grams) by its molar mass. The molar mass of ozone (O3) is approximately 48 g/mol.

Step 3: Use the stoichiometry of the reaction to find the number of moles of sodium iodide (NaI) needed. According to the balanced chemical equation, two moles of NaI react with one mole of O3. Therefore, the number of moles of NaI needed is twice the number of moles of O3.

Step 4: Calculate the mass of sodium iodide needed. This is done by multiplying the number of moles of NaI by its molar mass. The molar mass of NaI is approximately 150 g/mol.

Step 5: The result from step 4 is the mass of sodium iodide needed to remove the given amount of ozone. This is the final answer.

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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 chemists to calculate how much of a substance is needed or produced in a reaction based on balanced chemical equations. In this case, understanding the stoichiometric coefficients from the provided reaction is essential to determine the amount of sodium iodide required to react with a specific mass of ozone.

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, which is necessary for stoichiometric calculations. For sodium iodide (NaI), knowing its molar mass allows us to calculate how many grams are needed to react with the given amount of ozone.

Concentration and Mass Conversion

Concentration refers to the amount of a substance in a given volume of solution, while mass conversion involves changing units from mass to moles or vice versa. In this problem, converting the mass of ozone (1.3 mg) to moles is necessary to use stoichiometry effectively. This conversion is essential for determining how much sodium iodide is needed to completely react with the ozone present in the air sample.

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Textbook Question

A compound, Na2Cr2Ox, where x is unknown, is analyzed and found to contain 39.70% Cr. What is the value of x?

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Textbook Question

An element X forms an iodide (XI₃) and a chloride (XCl₃). The iodide is quantitatively converted to the chloride when it is heated in a stream of chlorine: 2 XI₃ + 3 Cl₂ → 2 XCl₃ + 3 I₂ If 0.5000 g of XI₃ is treated with chlorine, 0.2360 g of XCl₃ is obtained. (a) Calculate the atomic weight of the element X. (b) Identify the element X.

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Textbook Question

A method used by the U.S. Environmental Protection Agency (EPA) for determining the concentration of ozone in air is to pass the air sample through a 'bubbler' containing sodium iodide, which removes the ozone according to the following equation: O31g2 + 2 NaI1aq2 + H2O1l2¡ O21g2 + I21s2 + 2 NaOH1aq2 (a) How many moles of sodium iodide are needed to remove 5.95 * 10-6 mol of O3?

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Textbook Question

The fat stored in a camel's hump is a source of both energy and water. Calculate the mass of H2O produced by the metabolism of 1.0 kg of fat, assuming the fat consists entirely of tristearin 1C57H110O62, a typical animal fat, and assuming that during metabolism, tristearin reacts with O2 to form only CO2 and H2O.

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Open Question

When hydrocarbons are burned in a limited amount of air, both CO and CO2 form. When 0.450 g of a particular hydrocarbon was burned in air, 0.467 g of CO, 0.733 g of CO2, and 0.450 g of H2O were formed. (a) What is the empirical formula of the compound? (b) How many grams of O2 were used in the reaction? (c) How many grams would have been required for complete combustion?

Textbook Question

A mixture of N21g2 and H21g2 reacts in a closed container to form ammonia, NH31g2. The reaction ceases before either reactant has been totally consumed. At this stage 3.0 mol N2, 3.0 mol H2, and 3.0 mol NH3 are present. How many moles of N2 and H2 were present originally?

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