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.
Method
- Taste the lemon juice and vinegar. Do not taste the Hydrochloric acid as it is very toxic
- Place a small amount of baking soda into each of the three test tubes
- Add each of the three acids to into each of these test tubes
- Rinse out the test tubes and your skin if you come into contact with the acid
- Into each test tube pour one of the acids to a depth of 1 to 2 cm
- Add a small amount of litmus solution or a small piece of blue litmus paper to each of the test tubes
- Rinse out the test tubes
- Rinse out the test tubes
- Pour each of the acids into a test tube to a depth of 1-2cm
- Add a drop of Universal indicator solution of a small piece of universal indicator paper
- Show the results in a table
- Rinse the test tubes
- 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
| Acid | Taste | Baking Soda | Litmus | Universal indicator | Iron nail |
|---|---|---|---|---|---|
| Lemon Juice | Sour | Fizzes/Effervesce | Turns red | Orange (pH of 3-4) | Causes iron to rust |
| Vinegar | Sour | Fizzes/Effervesce | Turns red | Orange (pH of 3-4) | Causes iron to rust |
| Dilute Hydrochloric Acid | Do not taste it | Fizzes/Effervesce | Turns red | Red ( pH of 1-2) | The acid eats away the iron. The nail will disappear after a few days. |
Conclusion
- 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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