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Ch.10 - Gases: Their Properties & Behavior
Chapter 10, Problem 108d

Two 112-L tanks are filled with gas at 330 K. One contains 5.00 mol of Kr, and the other contains 5.00 mol of O2. Considering the assumptions of kinetic–molecular theory, rank the gases from low to high for each of the following properties. (d) Pressure

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1
Identify the ideal gas law equation: \( PV = nRT \).
Recognize that both gases are in identical conditions: same volume (112 L), same temperature (330 K), and same number of moles (5.00 mol).
Understand that according to the ideal gas law, pressure \( P \) is directly proportional to the number of moles \( n \), temperature \( T \), and inversely proportional to volume \( V \).
Since both gases have the same \( n \), \( T \), and \( V \), the pressure \( P \) for both gases will be the same.
Conclude that the pressure of Kr and O2 are equal, so they are ranked equally for pressure.

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Key Concepts

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

Kinetic-Molecular Theory

Kinetic-molecular theory explains the behavior of gases in terms of particles in constant motion. It posits that gas pressure results from collisions of gas molecules with the walls of their container. The speed and frequency of these collisions are influenced by temperature and the number of gas particles, which are crucial for understanding how different gases exert pressure.
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Ideal Gas Law

The ideal gas law, represented as PV = nRT, relates the pressure (P), volume (V), number of moles (n), gas constant (R), and temperature (T) of a gas. This law helps predict how changes in one variable affect the others. In this scenario, since both tanks have the same volume and temperature, the pressure will depend on the type of gas and its molecular characteristics.
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Molar Mass and Gas Behavior

Molar mass significantly influences the behavior of gases, particularly their speed and kinetic energy at a given temperature. Lighter gases, like Kr (krypton), will generally have higher average speeds than heavier gases, such as O2 (oxygen). This difference in molecular weight affects the frequency and force of collisions with the tank walls, thereby impacting the pressure exerted by each gas.
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