By the end of the lesson the learner can identify common acids and bases and their properties.
By the end of the lesson the learner can use indicators and the pH scale to classify a solution.
By the end of the lesson the learner can explain neutralisation and give Kenyan everyday examples.
Audio narration — reads aloud, works offline
Transcript
[0:00] Acids are substances that taste sour and turn blue litmus paper red. Lemon juice and vinegar are common examples.
[0:45] Bases feel slippery and turn red litmus paper blue. Soluble bases are called alkalis, like the sodium hydroxide in some soaps.
[1:35] The pH scale runs from 0 to 14. A pH below 7 is acidic, exactly 7 is neutral, and above 7 is basic or alkaline.
[2:25] Indicators such as litmus or universal indicator change colour to show how acidic or basic a solution is.
[3:15] When an acid reacts with a base, they cancel each other out in a reaction called neutralisation, forming a salt and water.
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