9. 3: The Acidic Environment
9. 3.1: Indicators were identified with the observation that the colour of some flowers depends on soil composition

Classify common substances as acidic, basic or neutral

Classify - Arrange or include in classes/categories

Acidic Basic Neutral

• Vinegar
• Lemon juice
• Acetic Acid
• Citric Acid
• Ascorbic acid
• Soda water * Cleaning things (window cleaner, soap etc.)
• Antacid tablets * Water
• Salt (sodium chloride)

Identify that indicators such as litmus, phenolphthalein, methyl orange and bromothymol blue can be used to determine the acidic or basic nature of a material over a range, and that the range is identified by change in indicator colour

Identify - recognise and name

Identify data and choose resources to gather information about the colour changes of a range of indicators

Identify - Recognise and name

1 - acid 7 - neutral 14 - basic

Indicator Range

1 7 14

Bromothymol blue Yellow I Blue

Litmus Red I Blue

Methyl orange Red I...