A Level Chemistry 2017 Paper 1 Question 5 Solution

In this video we want to discuss 2017 A Level H2 Chemistry Paper 1 Question 5.

Let's take a look at the question.

Topic tested is on Gaseous State.

For this question we want to use the Ideal Gas Equation to explain why a gas will liquefy under high pressure.

The most important formula in Gasesous State is the Ideal Gas Equation PV = nRT where:

P is pressure in Pa,
V is volume in m³,
n is moles of gas,
R is gas constant 8.31 J K^-1 mol^-1, and
T is temperature in K.

Using this equation we can predict changes in state of a gas when another state changes.

For example:

1. At constant temperature, pressure will increase when volume decrease (Boyle's Law)
2. At constant pressure, volume will increase when temperature increase (Charles' Law).

Option A

When pressure increase the temperature should also increase based on the Ideal Gas Equation so option A is not true.

Option B

When pressure increase, temperature increases which means the kinetic energy of molecules should also increase since KE is directly related to temperature.

Therefore option B is not true.

Option C

Increasing pressure will bring the molecules closer together but cannot change the size of the molecules.

Therefore option C is not true.

Option D

Increasing pressure will bring the molecules closer together so intermolecular forces get more effective and stronger.

This statement makes the most sense hence option D is our best answer.

Check out this video for the question and the suggested solution!

Topic: Gaseous State, Physical Chemistry, A Level Chemistry, Singapore

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