Chemical changes

Question 1

What is an indicator?

Answer 1

A dye that changes colour depnding on whether its above or below a certain pH.

Question 2

What is a base?

Answer 2

Any substance that will react with an acid to form a salt e.g. metal oxides/ hydroxides, metal carbonates.

Question 3

What is an acid?

Answer 3

A substance that forms an aqueous solution with a pH less than 7.

Acids form H+ ions in water.

Question 4

What is a alkali?

Answer 4

A base that dissolves in water to form a solution with a pH greater than 7.

Akalis form OH- ions in water.

Question 5

What is the reaction between acids and bases called?

Answer 5

Neutralisation:

acid + base —-> salt + water

Question 6

What is meant by the pH of an acid or alkali?

Answer 6

A measure of the concentration of H+ ions (proton) in the solution.

Question 7

For every decrease of 1 on the pH scale how does the concentration of H+ ions change?

Answer 7

Increases by a factor of 10.

Question 8

What is meant by an acids strength?

Answer 8

Tells you what proportion of the acid molecules ionise in water.

Question 9

What is meant by the concentration of an acid?

Answer 9

It measures how much acid there is in a certain volume of water.

Concentration is basically how watered down your acid is.

Question 10

What does an acid + metal carbonate react to form?

Answer 10

salt + water + carbon dioxide

Question 11

What does electrolysis mean?

Answer 11

Splitting up with electricity.