C8.7 - Energy and reversible reactions

Question 1

Energy cannot be created or destroyed in a chemical reaction.
What must the amount of energy transferred to the surroundings when the reaction goes in 1 direction in a reversible reaction be?

Answer 1

The amount of energy transferred to the surroundings when the reaction goes in 1 direction in a reversible reaction must be exactly the same as the energy transferred back in when the reaction goes in the opposite direction

Question 2

Why do blue copper(II) sulfate crystals contain water?

Answer 2

Blue copper(II) sulfate crystals contain water as part of the lattice formed when the copper(II) sulfate crystallised

Question 3

Blue copper(II) sulfate crystals contain water as part of the lattice formed when the copper(II) sulfate crystallised.
What is the copper(II) sulfate?

Answer 3

The copper(II) sulfate is hydrated

Question 4

Hydrated

Answer 4

Hydrated describes a substance that contains water in its crystals

Question 5

Blue copper(II) sulfate crystals contain water as part of the lattice formed when the copper(II) sulfate crystallised.
The copper(II) sulfate is hydrated.
What does heating the copper(II) sulfate do?

Answer 5

Heating the copper(II) sulfate drives off the water from the crystals

Question 6

Blue copper(II) sulfate crystals contain water as part of the lattice formed when the copper(II) sulfate crystallised.
The copper(II) sulfate is hydrated.
Heating the copper(II) sulfate drives off the water from the crystals, producing white anhydrous copper(II) sulfate.
What reaction is this?

Answer 6

This is an endothermic reaction

Question 7

Anhydrous

Answer 7

Anhydrous describes a substance that does not contain water

Question 8

What happens when you add water to anhydrous copper(II) sulfate?

Answer 8

When you add water to anhydrous copper(II) sulfate, hydrated copper(II) sulfate is formed

Question 9

When you add water to anhydrous copper(II) sulfate, hydrated copper(II) sulfate is formed.
What is a useful test for the presence of water?

Answer 9

A useful test for the presence of water is the colour change in the reaction, from white to blue

Question 10

What reaction is adding water to anhydrous copper(II) sulfate?

Answer 10

Adding water to anhydrous copper(II) sulfate is an exothermic reaction

Question 11

Adding water to anhydrous copper(II) sulfate is exothermic.

If you add water dropwise to anhydrous copper(II) sulfate powder, what may you see?

Answer 11

If you add water dropwise to anhydrous copper(II) sulfate powder, you may see steam rising

Question 12

What can you soak filter paper in?

Answer 12

You can soak filter paper in cobalt(II) chloride solution

Question 13

You can soak filter paper in cobalt(II) chloride solution and allow it to dry in an oven.
What is the blue paper that is produced?

Answer 13

The blue paper that is produced is called cobalt(II) chloride paper

Question 14

You can soak filter paper in cobalt(II) chloride solution and allow it to dry in an oven.
The blue paper that is produced is called cobalt(II) chloride paper.
What happens to the paper when water is added to it?

Answer 14

The cobalt(II) chloride paper turns pale pink when water is added to it

Question 15

Why can blue cobalt(II) chloride paper be used as an indicator for the presence of water?

Answer 15

Blue cobalt(II) chloride paper can be used as an indicator for the presence of water, because it turns pale pink when water is added to it

Question 16

Blue copper(II) sulfate crystals contain water as part of the lattice formed when the copper(II) sulfate crystallised.
The copper(II) sulfate is hydrated.
Heating the copper(II) sulfate drives off the water from the crystals, producing what?

Answer 16

Heating the copper(II) sulfate drives off the water from the crystals, producing white anhydrous copper(II) sulfate

Question 17

You can soak filter paper in cobalt(II) chloride solution and allow it to what?

Answer 17

You can:

1. Soak filter paper in cobalt(II) chloride solution
2. Allow it to dry in an oven