C5: Chemical Changes

Question 1

What is the most reactive element in the reactivity series?

Answer 1

Potassium

Question 2

What is the least reactive element in the reactivity series?

Answer 2

Platinum

Question 3

What will happen if a more reactive metal reacts with a less reactive metal?

Answer 3

The more reactive metal will displace the less reactive metal

Question 4

What happens when an acid reacts with a metal?

Answer 4

They produce a salt and hydrogen gas

Question 5

What happens when an acid reacts with a metal oxide?

Answer 5

They produce salt and water

Question 6

What happens when an acid reacts with a metal carbonate?

Answer 6

They produce salt, water and carbon dioxide

Question 7

What is an acid?

Answer 7

A substances that releases hydrogen (H+) ions when dissolved in water

Question 8

What is the defenition of an alkali?

Answer 8

A base which disolves in water and releases hydroxide ions (OH-) when dissolved in water

Question 9

What is a neutralisation reaction?

Answer 9

A reaction where an acid reacts with a base to form a salt and water

Question 10

What would you call a substance with a pH of less than 7?

Answer 10

An acid

Question 11

What is the range of the pH scale?

Answer 11

0-14

Question 12

What would you call a substance with a pH of exactly 7?

Answer 12

A neutral substances, such as pure water

Question 13

What are 2 ways of measuring the pH of a substance?

Answer 13

• Using an indicator such as a chemical dye which changes colour based on how acidic or alkali a substance is
• Using a pH probe, which tells you the pH of a substance

Question 14

Why might it be better to use a pH probe than a chemical dye to measure pH?

Answer 14

As the pH probe is likely to be more accurated then the chemical dye as it does not involve human judgement

Question 15

What would you call a substance with a pH of more than 7?

Answer 15

A base

Question 16

What are alkalis compared to bases?

Answer 16

Alkalis are a sub-group of bases which are soluble in water

Question 17

If a substances is a red or orange colour after using a chemical dye what pH’s is it likely to be?

Answer 17

Any pH from 0-6

Red from 0-3 and orange from 4-6

Question 18

If a substance is a blue or purple colour after using a chemical dye what pH is it likely to be?

Answer 18

pH of 8-14

8-10 for blue, 11-14 for purple

Question 19

If a substance is green after using a chemical dye what pH is it likely to be?

Answer 19

pH 7 (neutral)

Question 20

What gas is produced when a group 1 element reacts with water?

Answer 20

Hydrogen