You have a clear, colourless liquid. How can you find out safely whether it is an acid, a base or…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
You have a clear, colourless liquid. How can you find out safely whether it is an acid, a base or neutral?
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. Litmus. Dip blue and red litmus. If blue turns red, it is an acid. If red turns blue, it is a base. If neither changes, it is neutral.
Step 2. Better. Universal indicator or pH paper also tells you how strongly acidic or basic it is.
Answer: use indicators, never your tongue or fingers.
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