Name the colour that you see in each case…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Name the colour that you see in each case.
- Red litmus in lime water.
- Phenolphthalein in vinegar.
- Methyl orange in soap solution.
- Turmeric in lemon juice.
Need a reminder? The key ideaShow
Litmus: an acid turns blue litmus red, a base turns red litmus blue. Phenolphthalein is colourless in acids and pink in bases. Methyl orange is red in acids and yellow in bases. Turmeric is yellow, and turns reddish brown in bases. Onion, vanilla and clove oil lose their smell in a base.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Lime water is basic: red litmus turns blue.
Step 2. (b) Vinegar is acidic: phenolphthalein stays colourless.
Step 3. (c) Soap is basic: methyl orange turns yellow.
Step 4. (d) Lemon juice is acidic: turmeric stays yellow.
Answer: blue, colourless, yellow, yellow.
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