Chemistry: Gas Laws

What happens to pressure as we in crease kinetic energy?

• it decreases

• it remains constant

• it increases

• none of the above

Answer explanation

As kinetic energy increases, particles move faster, leading to more frequent and forceful collisions with surfaces. This results in an increase in pressure, making 'it increases' the correct choice.

In the picture when the pistons rise the volume of the cylinder decreases. What happens to the pressure and temperature?

• The temperature will decrease and, therefore, the pressure will decrease.

• The collisions between molecules and the container walls will increase causing an increase in pressure. The temperature will decrease because the kinetic energy decreases.

• The collisions between molecules and the container walls will increase causing an increase in pressure. The temperature will because the kinetic energy will increase.

• The temperature and pressure are not related.

Answer explanation

As the pistons rise, the volume decreases, leading to more frequent collisions of molecules with the walls, increasing pressure. The temperature rises because the kinetic energy of the molecules increases.

If you place a balloon in a refrigerator what will happen to the volume?

• it will decrease

• it will increase

• it will remain constant

• none of the above

Answer explanation

When a balloon is placed in a refrigerator, the temperature decreases. According to Charles's Law, the volume of a gas decreases as temperature decreases, so the volume of the balloon will decrease.

How do we measure an increase in kinetic energy?

• volume

• temperature

• Liters

• none of the above

Answer explanation

Kinetic energy is related to the motion of particles, which increases with temperature. As temperature rises, particles move faster, indicating an increase in kinetic energy. Thus, temperature is the correct measure.

The picture shows two completely identical mason jars. They're both filled with the same gas, only one of them has more in it (more molecules). What can you say about the pressures of both jars?

• P₁ > P₂ (greater pressure in jar 1)

• P₁< P₂ (greater pressure in jar 2)

• P₁ = P₂ (same pressure in both)

• There's not enough info to tell

How many kpa are in 1.01 bar?

• 760

• 101.3

• 14.7

• 1

Answer explanation

1 bar is equivalent to 101.3 kPa. Therefore, 1.01 bar equals 1.01 x 101.3 kPa, which is approximately 102.7 kPa. However, the question asks for the conversion of 1 bar, which is 101.3 kPa.

What temperature scale must we use in the Gas Laws?

• Rankine

• Fahrenheit

• Kelvin

• Celsius

Answer explanation

In Gas Laws, temperature must be measured in Kelvin because it is an absolute scale that starts at absolute zero, ensuring accurate calculations of gas behavior. Other scales like Celsius and Fahrenheit are not suitable.

What causes a hot air balloon to rise?

• An increase in temperature causes an increase in pressure that causes an increase in volume which causes the air in the balloon to be more dense than the air around it.

• An increase in temperature causes an increase in pressure that causes an increase in volume which causes the air in the balloon to be less dense than the air around it.

• As the temperature of the gas increases it escapes the balloon similarly to the gas leaving a rocket. This forces the balloon into the air.

• The increase in kinetic energy due to a temperature increase causes the atoms to lose protons and become helium. Helium is lighter than the air surrounding the balloon and this causes it to rise.

Answer explanation

The correct choice explains that increasing temperature causes the air inside the balloon to expand, making it less dense than the cooler air outside, allowing the balloon to rise.

When using Charles' Law if you double volume, what happens to temperature?

• it remains constant

• it triples

• it is divided by 2

• it is doubled also

Answer explanation

According to Charles' Law, if the volume of a gas is doubled at constant pressure, the temperature must also double to maintain the relationship between volume and temperature. Thus, the correct answer is that temperature is doubled also.

How many (partial pressures) gasses can we have in Dalton's Law?

• 5

• 10

• 100

• an infinite number of (partial pressures) gases

Answer explanation

According to Dalton's Law, the total pressure of a gas mixture is the sum of the partial pressures of each gas. There is no theoretical limit to the number of gases that can contribute, so we can have an infinite number of partial pressures.