Question

_{A drop of water is poured over a white powdery substance. Then it is observed that the substance turns blue. Answer the following questions :}

_{(i) What is the white powdery substance?}

_{(ii) Why does the substance change to blue colour?}

_{(iii) Write the chemical formula of the blue substance .}

_{(iv) Is the blue substance an acidic salt or a basic salt?}

_{(v) Give a reason for your answer in (iv).}

Answer 1

1. The white powder is anhydrous copper sulphate.

2. Blue substance is hydrated copper sulphate.It become blue because white copper sulphate absorb water and turn into blue.

3. CuSO4.5H2O is the chemical formula blue hydrated copper sulphate.

4. It is a salt, neither acidic nor base.

5. This is because it is found by the combination of Cu(OH)2 and H2SO4.