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Ch.10 - Gases: Their Properties & Behavior
Chapter 10, Problem 142

A 5.00-L vessel contains 25.0 g of PCl3 and 3.00 g of O2 at 15 °C. The vessel is heated to 200.0 °C, and the contents react to give POCl3. What is the final pressure in the vessel, assuming that the reaction goes to completion and that all reactants and products are in the gas phase?

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Key Concepts

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

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 calculating the final pressure in the vessel after the reaction, as it allows us to determine how changes in temperature and the number of moles affect the pressure of the gas mixture.
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Stoichiometry of the Reaction

Stoichiometry involves the calculation of reactants and products in chemical reactions based on balanced equations. Understanding the stoichiometry of the reaction between PCl3 and O2 to form POCl3 is crucial for determining the moles of each substance before and after the reaction, which directly influences the final pressure.
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Gas Phase Reactions

Gas phase reactions occur when reactants and products are in the gaseous state, allowing for the application of gas laws. In this scenario, recognizing that all substances are gases and that the reaction goes to completion is vital for accurately calculating the final pressure, as it affects the total number of moles present in the vessel.
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Related Practice
Textbook Question
A mixture of CS21g2 and excess O21g2 is placed in a 10.0-L reaction vessel at 100.0 °C and a pressure of 3.00 atm. A spark causes the CS2 to ignite, burning it completely, according to the equation CS21g2 + 3 O21g2¡CO21g2 + 2 SO21g2 After reaction, the temperature returns to 100.0 °C, and the mixture of product gases (CO2, SO2, and unreacted O2) is found to have a pressure of 2.40 atm. What is the partial pressure of each gas in the product mixture?
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Textbook Question
When 10.0 g of a mixture of Ca1ClO322 and Ca1ClO22 is heated to 700 °C in a 10.0-L vessel, both compounds decompose, forming O21g2 and CaCl21s2. The final pressure inside the vessel is 1.00 atm. (b) What is the mass of each compound in the original mixture?
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Textbook Question

When 10.0 g of a mixture of Ca(ClO3)2 and Ca(ClO)2 is heated to 700 °C in a 10.0-L vessel, both compounds decompose, forming O2(g) and CaCl2(s). The final pressure inside the vessel is 1.00 atm. (a) Write balanced equations for the decomposition reactions.

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Textbook Question

A steel container with a volume of 500.0 mL is evacuated, and 25.0 g of CaCO3 is added. The container and contents are then heated to 1500 K, causing the CaCO3 to decompose completely, according to the equation CaCO3(s) → CaO(s) + CO2(g). (a) Using the ideal gas law and ignoring the volume of any solids remaining in the container, calculate the pressure inside the container at 1500 K.

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Textbook Question

A steel container with a volume of 500.0 mL is evacuated, and 25.0 g of CaCO3 is added. The container and contents are then heated to 1500 K, causing the CaCO3 to decompose completely, according to the equation CaCO3(s) → CaO(s) + CO2(g). (b) Now make a more accurate calculation of the pressure inside the container. Take into account the volume of solid CaO (density = 3.34 g/mL) in the container, and use the van der Waals equation to calculate the pressure. The van der Waals constants for CO2(g) are a = 3.59 (L2-atm)/mol2 and b = 0.0427 L/mol.

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Textbook Question
An empty 4.00-L steel vessel is filled with 1.00 atm of CH41g2 and 4.00 atm of O21g2 at 300 °C. A spark causes the CH4 to burn completely, according to the equation CH41g2 + 2 O21g2¡CO21g2 + 2 H2O1g2 ΔH° = -802 kJ (a) What mass of CO21g2 is produced in the reaction?
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