KPT (Ex3) - Diffusion and Factors Affecting Diffusion

J/05/1

The experiment is set up as shown and left until there is no further change.

What is observed?

• a colourless layer below a purple layer

• a colourless liquid with the purple crystal unchanged

• a purple layer below a colourless layer

• a uniformly purple solution

J/05/4

A beaker of nitrogen is inverted over a porous pot containing carbon monoxide as shown. The water level does not change.

What is the reason for this?

• Nitrogen is almost inert.

• The two gases have equal molecular masses.

• Both gases have two atoms in a molecule.

• Neither gas is soluble in water.

Answer explanation

This is a diffusion question. It always revolves round the 2 factors that affect the rate of diffusion. 1) Temperature 2) Mass of particles. In this case, all gases is at the same temperature. Therefore must be the mass. If mass is equal for both gases, then the rate of diffusion should be the same.

JJ/08/3

Nitrogen dioxide is a dark brown gas and is more dense than air.

A gas jar containing nitrogen dioxide is sealed with a glass plate and is then inverted on top of a gas jar

containing air.

The glass plate is removed.

Which one of the following correctly describes the colours inside the gas jars after a long period of time?

• A

• B

• C

• D

J/09/1

An inflated balloon goes down because gas molecules can diffuse through the rubber.

Four balloons are filled with different gases at the same temperature and pressure.

Which balloon would go down quickest?

• 
• 
• 
• 

J/11/1

A drop of liquid bromine is placed in the bottom of a gas jar. Brown fumes of bromine vapour slowly spread through the covered gas jar.

Why does this happen?

• Bromine vapour is less dense than air.

• Bromine molecules and the molecules in air are always moving around.

• Bromine molecules are smaller than the molecules in air.

• Bromine molecules move faster than the molecules in air.

J/15/8

Which row shows correct statements about the speed at which a gas diffuses?

• A

• B

• C

• D

J/18/4

Two gases, ammonia and hydrogen chloride, at an equal pressure, are allowed to enter the apparatus shown.

After a time, a white solid forms on the inside of the tube.

Which statements explain why a white solid forms in the position shown?

1 Ammonia and hydrogen chloride react to form solid ammonium chloride.

2 Ammonia diffuses faster than hydrogen chloride.

3 Ammonia has a lower relative molecular mass than hydrogen chloride.

• 1, 2 and 3

• 1 and 2 only

• 1 only

• 2 and 3 only

Answer explanation

Hydrochloric acid forms hydrogen chloride gas

1) NH3 + HCl --> NH4Cl

2) Ammonia is lighter than hydrogen chloride

3) NH3 = 17, HCl = 36.5 (NH3 is lighter than HCl)

N/05/3

The coverplate is removed from the gas jars shown in the diagram.

After several days, the colour of the gas is the same in both jars.

Which statement explains this change?

• Oxygen and bromine gases have equal densities.

• Oxygen and bromine molecules are in random motion.

• Oxygen and bromine molecules diffuse at the same rate.

• Equal volumes of oxygen and bromine contain equal numbers of molecules.

Answer explanation

Hydrochloric acid forms hydrogen chloride gas

1) NH3 + HCl --> NH4Cl

2) Ammonia is lighter than hydrogen chloride

3) NH3 = 17, HCl = 36.5 (NH3 is lighter than HCl)

N/08/8

Which gas diffuses at the same rate as nitrogen gas, N₂?

• carbon dioxide

  CO₂

• carbon monoxide

  CO

• neon

  Ne

• sulphur dioxide

  SO₂

Answer explanation

Calculate the RMM for all the gases. And see which gas has the same mass (RMM) as nitrogen gas, N₂

N/09/2

Why does neon gas, Ne, diffuse faster than carbon dioxide gas, CO2?

• Neon atoms have the lower mass.

• Neon does not form molecules.

• Neon is a noble gas.

• Neon is less dense than air.

Answer explanation

Calculate the RMM for all the gases. And see which gas has the same mass (RMM) as nitrogen gas, N₂