Universal paper can be used to test the acidity of a solution. Image credit MediaWiki

Universal paper can be used to test the acidity of a solution. Image credit MediaWiki

ZIMSEC O Level Combined Science Notes: Experiment: The properties of acids

Aim:  Investigating the properties of acids

Materials: Dilute hydrochloric acid, vinegar, lemon juice, sodium hydrogen carbonate (baking soda), blue litmus paper/litmus solution, universal indicator paper, iron nail, test tubes, spatula.


  1. Taste the lemon juice and vinegar. Do not taste the Hydrochloric acid as it is very toxic
  2. Place a small amount of baking soda into each of the three test tubes
  3. Add each of the three acids to into each of these test tubes
  4. Rinse out the test tubes and your skin if you come into contact with the acid
  5. Into each test tube pour one of the acids to a depth of 1 to 2 cm
  6. Add a small amount of litmus solution or a small piece of blue litmus paper to each of the test tubes
  7. Rinse out the test tubes
  8. Rinse out the test tubes
  9. Pour each of the acids into a test tube to a depth of 1-2cm
  10. Add a drop of Universal indicator solution of a small piece of  universal indicator paper
  11. Show the results in a table
  12. Rinse the test tubes
  13. Put an iron nail into one of the test tube and pour hydrochloric acid over it and leave the test tube over a few days

Results and observations

AcidTasteBaking SodaLitmusUniversal indicatorIron nail
Lemon JuiceSourFizzes/EffervesceTurns redOrange (pH of 3-4)Causes iron to rust
VinegarSourFizzes/EffervesceTurns redOrange (pH of 3-4)Causes iron to rust
Dilute Hydrochloric AcidDo not taste itFizzes/EffervesceTurns redRed ( pH of 1-2)The acid eats away the iron. The nail will disappear after a few days.


  • Acids have a sour taste
  • They effervesce when they are mixed with baking soda (and some bases)
  • They turn litmus paper red
  • turn Universal indicator red, orange  or yellow (very weak acids such as acid rain)
  • Cause iron to rust also dissolve

To access more topics go to the Combined Science Notes page.

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