Q: Why does H$_2$O deviate more from ideal gas behavior than CH$_4$?

H$_2$O has stronger intermolecular forces.

Question 1

Which assumption of the Kinetic Molecular Theory is most responsible for the failure of the Ideal Gas Law at high pressures?

Accepted Answer

Gas particles do not exert attractive or repulsive forces on each other.

Question 2

Which of the following gases is most likely to behave ideally under standard conditions (1 atm, 298 K)?

Accepted Answer

H$_2$

Question 3

The van der Waals equation for real gases is given by

$\left(P + a \left(\frac{n}{V}\right)^2\right)(V - nb) = nRT$

What does the parameter $b$ correct for?

Accepted Answer

The finite volume of gas particles

Question 4

At low temperatures, real gases deviate from ideal behavior primarily because:

Accepted Answer

Intermolecular attractions become significant.

Question 5

Which correction in the van der Waals equation becomes most significant at high pressures?

Accepted Answer

The $b$ parameter

Question 6

A sample of 1.00 mol of CO$_2$ is confined in a 1.00 L container at 300 K. Using the van der Waals constants $a = 3.59$ L$^2$ atm/mol$^2$ and $b = 0.0427$ L/mol, which equation would you use to calculate the real pressure?

Accepted Answer

$P = \frac{nRT}{V - nb} - a\left(\frac{n}{V}\right)^2$

Question 7

Why does H$_2$O deviate more from ideal gas behavior than CH$_4$?

Accepted Answer

H$_2$O has stronger intermolecular forces.

Question 8

Which of the following conditions would make a gas behave most ideally?

Accepted Answer

Low pressure and high temperature

Question 9

A real gas is compressed to a very small volume. Which van der Waals correction becomes most important and why?

Accepted Answer

The $b$ correction, because the finite size of particles becomes significant.

Question 10

Which of the following best explains why the pressure of a real gas is lower than predicted by the ideal gas law at moderate pressures?

Accepted Answer

Gas particles exert attractive forces, reducing the force of collisions with the container walls.

Question 11

Given the van der Waals constants for two gases, which gas would you expect to deviate more from ideal behavior at low temperatures?

Accepted Answer

The gas with the larger $a$ value.

Question 12

Which of the following is NOT an assumption of the Kinetic Molecular Theory?

Accepted Answer

Gas particles exert attractive and repulsive forces on each other.

Question 13

A gas sample behaves more ideally when:

Accepted Answer

The particles are small and nonpolar.

Question 14

If the van der Waals constant $a$ for a gas is very large, what does this indicate about the gas?

Accepted Answer

The gas has strong intermolecular attractions.

Question 15

Which real-world scenario would most likely require the use of the van der Waals equation instead of the ideal gas law?

Accepted Answer

Calculating the pressure of carbon dioxide at 100 atm and 250 K.

Question 16

Which of the following best describes the effect of intermolecular forces on the measured pressure of a real gas?

Accepted Answer

They decrease the measured pressure.

Question 17

A gas sample is cooled at constant volume. Which van der Waals correction becomes more significant and why?

Accepted Answer

The $a$ correction, because attractive forces become more significant at lower temperatures.

Question 18

Which of the following gases would you expect to have the largest van der Waals $a$ constant?

Accepted Answer

CO$_2$

Question 19

Why is the volume available to a real gas less than the volume of the container?

Accepted Answer

Gas particles occupy a finite volume.

Question 20

A 1.00 mol sample of a gas is confined in a 1.00 L container at 300 K. If the measured pressure is significantly lower than predicted by the ideal gas law, what is the most likely explanation?

Accepted Answer

The gas particles exert significant attractive forces.

Real Gases and Deviations from Ideal Gas Behavior

Study Guide - Practice Questions

Study Guide - Flashcards