Complete the following paragraph using the words in bold. Acids taste _ and feel on the skin. Strong acids can burn your skin. We say these acids are . Bases taste and feel . A base that can dissolve

here are the answers to the activity and questions:

Science language activity

Complete the following paragraph using the words in bold.

Acids taste sour and feel rough on the skin. Strong acids can burn your skin. We say these acids are corrosive. Bases taste bitter and feel slippery. A base that can dissolve in water is called an alkali. Neutrals are neither acids nor bases. An indicator is a dye that changes colour in chemicals. Acids will turn blue litmus red and bases will turn red litmus blue.

Test yourself

1. Give two examples of everyday materials that contain:

• a) acid: Vinegar, Lemon juice
• b) alkali: Soap, Toothpaste

2. a) Name two citrus fruits.

• Lemon, Orange

2. b) Describe the taste of citrus fruits.

• Sour

2. c) Are citrus fruits acidic or basic?

• Acidic

2. d) Give the name of the acid or base that you find in citrus fruits.

• Citric acid

3. Red litmus indicator was used to test toothpaste. It turned blue. Explain what this tells you about toothpaste.
When red litmus paper turns blue, it indicates that the substance is basic or alkaline. Therefore, toothpaste is a base.

4. What colour would blue litmus paper be in these substances?

• a) Fizzy drink: Red (acidic)
• b) Water: Blue (neutral, no change)
• c) Sugar solution: Blue (neutral, no change)
• d) Soap: Blue (basic, no change)
• e) Orange juice: Red (acidic)
• f) Bicarbonate of soda: Blue (basic, no change)
• g) Salt solution: Blue (neutral, no change)

5. Use the photograph in Figure 18 to answer these questions.

• a) Write down the name of the acid in the bottle.
  • Ethanoic acid
• b) Give the more common name for this acid.
  • Acetic acid (or vinegar when diluted)
• c) What hazard symbol do you see on the bottle?
  • The corrosive symbol (a hand and a surface being corroded).
• d) Explain what the hazard symbol means.
  • It means the substance can cause severe skin burns and eye damage or corrode metals.
• e) Would red litmus paper change colour in this acid?
  • No, red litmus paper would remain red in an acid. Acids only turn blue litmus paper red.