7F — Acids and Alkalis

Question 1

1) What is a hazard?
2) What is a risk?
3) How can risks be reduced?

Answer 1

1) A hazard is something that can cause harm.
2) A risk is the chance that a hazard will actually cause harm.
3) Risks can be reduced by taking precautions.

Question 2

1) What is an acid?

2) What are examples of acids?

Answer 2

1) A substance that turns litmus red. It has a pH of less than 7. They have a sour taste.
2) Common substances at home that contain acids include: citric acid, vinegar, fizzy drinks and car battery acid.

Question 3

1) What are alkalis?
2) What substances are alkalis?
3) What is a base?

Answer 3

1) A substance that turns litmus blue. It has a pH of more than 7. Many alkalis are metal hydroxide solutions.
2) Common substances at home that contain alkalis include: toothpaste, drain cleaner, oven cleaner.
3) A base is any substance, soluble or insoluble,
that neutralises an acid forming a salt and water.

Question 4

1) What is an indicator?

2) What colours do litmus change?

Answer 4

1) Indicators change colour and can be used to detect acids, alkalis and neutral solutions.
2) Litmus changes an acid red, an alkali blue, and a neutral substance purple.

Question 5

What is neutralisation?

Answer 5

Neutralisation is a reaction between an acid and an alkali.

acid + alkali —> salt + water