Chemistry Unit 1 PPQs

Question 1

Q1c - Suggest one reason why it took five minutes for the white ring to form.

Answer 1

Particles move in random directions and need many collisions for the white ring to become visible

Question 2

Q1b - The experiment was repeated at a higher temperature: State and explain how this change would affect the time taken for the white ring to form

Answer 2

The temperature increase will affect the time taken because it means they will have more kinetic energy so they will move faster and therefore the time taken for diffusion decreases

Question 3

Q2c (ii) - Write an equation, including state symbols, for the change in state from steam to water

Answer 3

H20 (g) -> H20 (l)

Question 4

Q5b - Describe what happens when water vapor cools to form liquid water in terms of change in energy

Answer 4

The energy decreases as liquids have less energy than gas. This is because liquids have more bonds of attraction then gas so they can’t move as much or as freely as gas

Question 5

Q5b - Describe what happens when water vapor cools to form liquid water in terms of change in arrangement

Answer 5

The particles move closer and are arranged to have definite volume but not shape

Question 6

Q5b - Describe what happens when water vapor cools to form liquid water in terms of change in movement

Answer 6

The movement will be slower, not as free to move, and also less randomly

Question 7

Q8c (iii) - Suggest why the liquid in the beaker needs to be stirred constantly

Answer 7

To avoid the bottom of the liquid from overheating and the bottom getting hotter than the rest of the liquid

Question 8

Q13 (ii) - Much more oxygen can be stored in the tank when the oxygen is a liquid rather than a gas. Give a reason for this in terms of the arrangements of the particles

Answer 8

The reason is that they are more closely packed together than gas and less space between the particles as well

Question 9

Q17b (ii) - Explain in terms of particles, why change differs when hot water is used instead of cold water

Answer 9

This is because if the water is hot, it makes the particles move more because heat increases the kinetic energy of particles. So there is space for the diffused crystals to diffuse and dissolve in the water because the particles will move more.