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Ch.10 - Gases
Chapter 10, Problem 126b

Gaseous iodine pentafluoride, IF5, can be prepared by the reaction of solid iodine and gaseous fluorine: I2(s) + 5 F2(g) → 2 IF5(g) A 5.00-L flask containing 10.0 g of I2 is charged with 10.0 g of F2, and the reaction proceeds until one of the reagents is completely consumed. After the reaction is complete, the temperature in the flask is 125 °C. (b) What is the mole fraction of IF5 in the flask?

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First, calculate the number of moles of I2 and F2 using their molar masses. The molar mass of I2 is approximately 253.8 g/mol, and the molar mass of F2 is approximately 38.0 g/mol. Use the formula: \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \).
Determine the limiting reagent by comparing the mole ratio of I2 and F2 to the stoichiometry of the reaction. The balanced equation shows that 1 mole of I2 reacts with 5 moles of F2. Calculate the moles of each reactant and compare to find which one is the limiting reagent.
Calculate the moles of IF5 produced using the stoichiometry of the reaction. Since the reaction produces 2 moles of IF5 for every 1 mole of I2 consumed, use the moles of the limiting reagent to find the moles of IF5 formed.
Calculate the total moles of gas in the flask after the reaction. This includes the moles of IF5 produced and any excess moles of the non-limiting reagent that remain unreacted.
Finally, calculate the mole fraction of IF5 in the flask. The mole fraction is given by the formula: \( \text{mole fraction of IF5} = \frac{\text{moles of IF5}}{\text{total moles of gas}} \).

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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 equation. It allows us to determine the amount of product formed or reactants consumed by using mole ratios derived from the coefficients in the balanced equation. In this case, the stoichiometric coefficients indicate that 1 mole of I2 reacts with 5 moles of F2 to produce 2 moles of IF5.
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Mole Fraction

Mole fraction is a way of expressing the concentration of a component in a mixture, defined as the ratio of the number of moles of that component to the total number of moles of all components in the mixture. It is a dimensionless quantity and is useful for understanding the composition of gaseous mixtures, such as the one formed in this reaction. The mole fraction of IF5 can be calculated after determining the moles of all species present.
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Ideal Gas Law

The Ideal Gas Law relates the pressure, volume, temperature, and number of moles of a gas through the equation PV = nRT. This law is essential for understanding the behavior of gases under various conditions. In this scenario, it can be used to find the total number of moles of gas in the flask after the reaction, which is necessary for calculating the mole fraction of IF5.
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Related Practice
Textbook Question

Natural gas is very abundant in many Middle Eastern oil fields. However, the costs of shipping the gas to markets in other parts of the world are high because it is necessary to liquefy the gas, which is mainly methane and has a boiling point at atmospheric pressure of -164 °C. One possible strategy is to oxidize the methane to methanol, CH3OH, which has a boiling point of 65 °C and can therefore be shipped more readily. Suppose that 3.03×108 m3 of methane at atmospheric pressure and 25 °C is oxidized to methanol. (a) What volume of methanol is formed if the density of CH3OH is 0.791 g/mL?

Textbook Question

Gaseous iodine pentafluoride, IF5, can be prepared by the reaction of solid iodine and gaseous fluorine: I2(s) + 5 F2(g) → 2 IF5(g) A 5.00-L flask containing 10.0 g of I2 is charged with 10.0 g of F2, and the reaction proceeds until one of the reagents is completely consumed. After the reaction is complete, the temperature in the flask is 125 °C. (a) What is the partial pressure of IF5 in the flask?

Textbook Question

Gaseous iodine pentafluoride, IF5, can be prepared by the reaction of solid iodine and gaseous fluorine: I2(s) + 5 F2(g) → 2 IF5(g) A 5.00-L flask containing 10.0 g of I2 is charged with 10.0 g of F2, and the reaction proceeds until one of the reagents is completely consumed. After the reaction is complete, the temperature in the flask is 125 °C.  (c) Draw the Lewis structure of IF5.

Textbook Question

Gaseous iodine pentafluoride, IF5, can be prepared by the reaction of solid iodine and gaseous fluorine: I2(s) + 5 F2(g) → 2 IF5(g) A 5.00-L flask containing 10.0 g of I2 is charged with 10.0 g of F2, and the reaction proceeds until one of the reagents is completely consumed. After the reaction is complete, the temperature in the flask is 125 °C. (d) What is the total mass of reactants and products in the flask?

Textbook Question

A 6.53-g sample of a mixture of magnesium carbonate and calcium carbonate is treated with excess hydrochloric acid. The resulting reaction produces 1.72 L of carbon dioxide gas at 28 °C and 99.06 kPa pressure. (a) Write balanced chemical equations for the reactions that occur between hydrochloric acid and each component of the mixture.