Diffusion

A gas cylinder is positioned in each corner of a square-shaped room. Each cylinder holds a different gas at the same pressure. The gases are let out at the same instant. Which gas will arrive at the centre of the room first?

May/June 2015

Which row gives the correct statements about how quickly a gas diffuses?

May/June 2015

Gases are able to diffuse through porous pots. The diagram shows a beaker filled with nitrogen turned upside down over a porous pot that contains carbon monoxide. The water level stays still. Which statement explains this?

May/June 2016

Gases are able to diffuse through porous pots. The diagram shows a beaker filled with nitrogen turned upside down above a porous pot containing carbon monoxide. The water level remains unchanged. Which statement explains this?

May/June 2016

Esters, such as propyl ethanoate, are frequently employed as solvents.

May/June 2016

Which statement best accounts for the fact that chlorine, $\text{Cl}_2$, at $40\,^{\circ}\text{C}$ diffuses more slowly than neon, $\text{Ne}$, at $20\,^{\circ}\text{C}$?

May/June 2017

At room temperature, methane, ethane and propane are all gases.

May/June 2017

Which substance would diffuse at the fastest rate?

May/June 2018

Two gases, ammonia and hydrogen chloride, are introduced into the apparatus shown at the same pressure. After some time, a white solid appears on the inner surface of the tube. Which statements account for the white solid forming in the position shown?

May/June 2018

Under which conditions will a gas diffuse at the highest rate?

May/June 2019

At the same temperature and pressure, which gas diffuses most quickly?

May/June 2019

Ethylamine gas, $\text{C}_2\text{H}_5\text{NH}_2$, reacts with hydrogen chloride gas, $\text{HCl}$, to produce a white solid called ethylamine hydrochloride. In which part of the tube would a ring of solid white ethylamine hydrochloride appear?

May/June 2022

When ethylamine gas, $\text{C}_2\text{H}_5\text{NH}_2$, reacts with hydrogen chloride gas, $\text{HCl}$, a white solid called ethylamine hydrochloride is produced. In the tube, at which point would a ring of solid white ethylamine hydrochloride appear?

May/June 2022

The four gases below are given. 1 $\text{CH}_4$ 2 $\text{NH}_3$ 3 $\text{CO}_2$ 4 $\text{N}_2$ In what sequence do they diffuse most rapidly at room temperature and pressure?

May/June 2025

A gas is formed by a chemical reaction at one end of a laboratory. After a few minutes, it is found at the opposite end of the laboratory. Which process explains why the gas is detected at the other end of the laboratory?

May/June 2025

Two containers, one containing methane and the other containing butane, are positioned at the same distance from a naked flame. The two gases are then released together. The methane reaches the flame and ignites before the butane gets there. Which statement best explains this?

Oct/Nov 2015

Two students arranged the tubes as shown. Cotton wool dipped in concentrated hydrochloric acid gives off hydrogen chloride fumes. Cotton wool dipped in concentrated hydrobromic acid gives off hydrogen bromide fumes.

Oct/Nov 2015

The four gases below are given. 1 $\text{CH}_4$ 2 $\text{NH}_3$ 3 $\text{CO}_2$ 4 $\text{N}_2$ A $1\,\text{mol dm}^{-3}$ sample of each of gases 1-4 is allowed to diffuse. In what sequence do their diffusion rates occur at room temperature and pressure?

Oct/Nov 2016

Under identical conditions, which gas diffuses at the same rate as nitrogen?

Oct/Nov 2016

A purple pill is put into a beaker containing water. The beaker is then left for several hours. The diagram shows how the water looks when the pill is added and again several hours later. Which statement explains the reason for this change?

Oct/Nov 2017

The diffusion rates of carbon dioxide and methane are compared at two temperatures, one high and one low. Which row correctly identifies the gas that diffuses more quickly and the temperature at which diffusion occurs most rapidly?

Oct/Nov 2021

A gas sample is let out from a fixed location in a laboratory. A detector is positioned ten metres away from the release point. It measures and notes the time at which the gas concentration reaches ten molecules per million molecules of air. The investigation is done using two gases at different temperatures. In which experiment was the time shown by the detector the largest?

Oct/Nov 2021

At the same pressure, which gas has the highest diffusion rate?

Oct/Nov 2022

Information on two compounds is shown below. Both compounds have simple molecular structures. Compound data: - $\text{H}_2\text{S}$: melting point $-85\,^{\circ}\text{C}$, boiling point $-61\,^{\circ}\text{C}$ - $\text{PCl}_3$: melting point $-112\,^{\circ}\text{C}$, boiling point $76\,^{\circ}\text{C}$ Two bottles are positioned close to each other inside a large container kept at $90\,^{\circ}\text{C}$. One bottle holds $1.0\,\text{g}$ of $\text{H}_2\text{S}$, and the other holds $1.0\,\text{g}$ of $\text{PCl}_3$. A detector is located in the container $2.0\,\text{m}$ from the two bottles. The bottles are opened simultaneously. Which row gives the correct answer?

Oct/Nov 2023

A crystal of sodium chloride is put into a beaker of water and it dissolves. This process can be split into four stages. At which stages does diffusion occur?

Oct/Nov 2023

If temperature and pressure are kept the same, which gas diffuses at the same rate as nitrogen?

Oct/Nov 2024

Helium gas and argon gas are combined in a sealed container at room temperature and pressure (r.t.p.). What occurs when both gases are in the container?

Oct/Nov 2024

Which substance would diffuse the fastest?

Oct/Nov 2025