ZIMSEC O Level Combined Science Notes: Experiment: Making acidic and alkaline solutions
Aim: To make acidic and alkaline solutions
Materials: sodium oxide, magnesium oxide, aluminium oxide, zinc oxide, unversal indicator, deflagrating spoon, sulpher, powdered carbon
Method
- Dissolve a very small amount of sodium oxide in half a test tube of water
- Add 2 drops of universal indicator solution and note the pH of the solution
- Repeat the experiment using magnesium oxide, zince oxide and aluminium oxide taking note of the pH each time
- The oxide of sulpher is a gas. Set up the experiment as shown above by burning a small amount of sulpher in a deflagrating spoon and collecting the gas in a gas jar
- Add about 10cm3 of water into the gas jar, cover it and shake well
- Add Universal indicator to the solution and take note of its pH
- Repeat the steps using powdered carbon instead of sulpher
Results and Observations
Oxide | pH of solution | Soluble/Insoluble in water |
---|---|---|
Sodium oxide | Strong alkaline/Base | Reacts violently with water which is visible in the water solution |
Magnesium oxide | Alkaline/Basic | Not soluble/very small amounts dissolve |
Aluminium oxide | Alkaline/Basic | Is insoluble |
Zinc oxide | Alkaline | Is insoluble |
Sulpher dioxide | strong acid | Fairly soluble |
Carbon dioxide | weak acid | very small amounts dissolve |
Conclusion
- The oxides of metals form bases
- Their solutions when they do dissolve in water are alkali
- The oxides of non-metals form acids
- Their solutions when they dissolve in water are acidic
NB The bases listed above react with the water which gives the impression of them dissolving
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