Problem 83 - Chemistry Central Science

Question

(a) List two experimental conditions under which gases deviate from ideal behavior. (b) List two reasons why the gases deviate from ideal behavior. (c) Explain how the function \(P V / R T\) can be used to show how gases behave nonideally.

Step-by-Step Solution

Answer

(a) Two experimental conditions under which gases deviate from ideal behavior are high pressure and low temperature. (b) Gases deviate from ideal behavior due to intermolecular forces and the finite size of molecules. (c) The function \(PV/RT\) can be used to show how gases behave nonideally by comparing its calculated value to the ideal value of 1. A value different from 1 indicates nonideal behavior, influenced by experimental conditions and the type of gas being observed.

Step 1: (a) Experimental Conditions of Deviation from Ideal Behavior

Two experimental conditions under which gases deviate from ideal behavior are: 1. High pressure: The deviation from ideal behavior becomes more significant when gases are subjected to high pressure, as the gas molecules are forced closer together and can no longer be treated as points. 2. Low temperature: At low temperatures, the speed of gas molecules decreases, increasing the chance of intermolecular attractions, which in turn cause more significant deviations from ideal behavior.

Step 2: (b) Reasons for Deviation from Ideal Behavior

There are two primary reasons why gases deviate from ideal behavior: 1. Intermolecular forces: In an ideal gas, it is assumed that there are no intermolecular forces between gas molecules. However, in reality, gas molecules are influenced by weak attractive and repulsive forces. These interactions lead to deviation from ideal behavior. 2. Finite size of molecules: Ideal gas assumptions state that gas molecules have no volume or size. However, in real gases, molecules have a finite size, and when the volume or pressure becomes significant, the volume occupied by the gas molecules themselves will affect the behavior of the gas.

Step 3: (c) Using the Function \(PV/RT\) to Show Nonideal Behavior

The function \(PV/RT\) is used to describe the behavior of a gas: - \(P\) represents pressure - \(V\) represents volume - \(R\) is the gas constant - \(T\) is the temperature For an ideal gas, the value of \(PV/RT\) should be equal to 1 at all conditions. However, in real gases, deviations from ideal behavior result in the value of \(PV/RT\) being either greater or lesser than 1, depending on the experimental conditions and type of gas. When \(PV/RT\) is greater than 1, it indicates that the gas is experiencing stronger intermolecular forces and/or larger molecular volume than what the ideal gas model assumes. This is typically observed when gases are under high pressure or at low temperatures. On the other hand, when \(PV/RT\) is less than 1, it means that the gas is behaving more ideally than under normal circumstances, which can be attributed to reduced intermolecular forces or negligibly small molecular volume. In conclusion, the function \(PV/RT\) can be used to demonstrate how gases deviate from ideal behavior by comparing its calculated value to the ideal value of 1. A value different from 1 is indicative of nonideal behavior, with deviations influenced by experimental conditions and the type of gas being observed.