A scientist cooled the air inside a container: The temperature of the air changed from 20 °C to 0 °C Explain how the motion of the air molecules caused the pressure in the container to change as the temperature decreased - AQA - GCSE Physics Combined Science - Question 2 - 2019 - Paper 1

The internal energy change when water freezes is given as 0.70 kJ. Using the specific latent heat of fusion:

$m = \frac{Q}{L_f}$

where:

• $Q = 0.70$ kJ = 700 J
• $L_f = 330$ kJ/kg = 330000 J/kg

Substituting the values:

$m = \frac{700}{330000} = 0.00212 \text{ kg}$.

Thus, the mass of ice produced is approximately 0.0021 kg.

As the temperature of the argon decreases from 20 °C to -190 °C, the particles lose kinetic energy.

1. Gas Phase: At higher temperatures, argon particles move freely and are spaced apart, allowing them to collide with one another and the walls of the container.

2. Liquid Phase: As cooling continues, the particles begin to lose speed and come closer together, forming a liquid state. They flow past each other but maintain a definite volume.

3. Solid Phase: Eventually, at lower temperatures, the particles arrange themselves in a fixed structure, becoming a solid. In this state, they vibrate closely around fixed positions, resulting in a solid form of argon.