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Ch.10 - Gases
Chapter 10, Problem 63

A mixture containing 0.50 mol H2(g), 1.00 mol O2(g), and 3.50 mol N2(g) is confined in a 25.0-L vessel at 25 °C. Calculate the partial pressure of H2, O2, and N2.

Verified step by step guidance
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Step 1: Use the ideal gas law to find the total pressure of the gas mixture. The ideal gas law is given by the equation: \( PV = nRT \), where \( P \) is the pressure, \( V \) is the volume, \( n \) is the number of moles, \( R \) is the ideal gas constant (0.0821 L·atm/mol·K), and \( T \) is the temperature in Kelvin. First, convert the temperature from Celsius to Kelvin by adding 273.15 to the Celsius temperature.
Step 2: Calculate the total number of moles in the mixture by adding the moles of each gas: \( n_{\text{total}} = n_{\text{H}_2} + n_{\text{O}_2} + n_{\text{N}_2} \).
Step 3: Substitute the total number of moles, the volume of the vessel, the temperature in Kelvin, and the ideal gas constant into the ideal gas law equation to solve for the total pressure \( P_{\text{total}} \).
Step 4: Use Dalton's Law of Partial Pressures to find the partial pressure of each gas. According to Dalton's Law, the partial pressure of a gas in a mixture is equal to the mole fraction of that gas multiplied by the total pressure. Calculate the mole fraction of each gas: \( \text{Mole fraction of } H_2 = \frac{n_{\text{H}_2}}{n_{\text{total}}} \), \( \text{Mole fraction of } O_2 = \frac{n_{\text{O}_2}}{n_{\text{total}}} \), \( \text{Mole fraction of } N_2 = \frac{n_{\text{N}_2}}{n_{\text{total}}} \).
Step 5: Calculate the partial pressure of each gas by multiplying its mole fraction by the total pressure: \( P_{\text{H}_2} = \text{Mole fraction of } H_2 \times P_{\text{total}} \), \( P_{\text{O}_2} = \text{Mole fraction of } O_2 \times P_{\text{total}} \), \( P_{\text{N}_2} = \text{Mole fraction of } N_2 \times P_{\text{total}} \).

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 behavior of gases under various conditions, allowing us to determine the pressure exerted by a gas in a mixture when its amount, volume, and temperature are known.
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Partial Pressure

Partial pressure is the pressure that a single gas in a mixture would exert if it occupied the entire volume alone. According to Dalton's Law of Partial Pressures, the total pressure of a gas mixture is the sum of the partial pressures of each individual gas, which can be calculated using the Ideal Gas Law for each component.
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Molar Volume of a Gas

At standard temperature and pressure (STP), one mole of an ideal gas occupies approximately 22.4 liters. However, in this scenario, we are using a specific volume (25.0 L) and temperature (25 °C), which requires the use of the Ideal Gas Law to find the partial pressures based on the number of moles and the conditions provided.
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