While sitting in the lab you noticed a flask containing a clear colourless liquid on your desk (label is missing). Conveniently a science kit containing some indicators was found right beside the flask. The indicators present in the science kit were universal indicator paper (with colour chart), red litmus paper and blue litmus paper. Explain one test you could perform on the unknown liquid to determine if the liquid is an acid or a base
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Answer:
The secret of this magic color change is pH. Chemicals with a low pH (0-6) are acidic, while those with a high pH (8-14) are basic. (A pH of 7 is neutral: neither acidic nor basic.) Universal indicator is a chemical that changes color in the presence of acids and bases from a pH of 2 to 10. Acids turn the indicator red, pink, orange, and yellow, while bases turn it green, blue, and purple. Vinegar is an acid, so when you poured the indicator solution into the second flask, it turned red. Ammonia is a base, so when you mixed the acidic vinegar solution with ammonia, it raised the pH and the water turned blue. If you had enough vinegar in your last flask, the solution should have turned red again. (If it didn’t, try adding a little more vinegar.)