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ICSE Class 10 Chemistry Question 14 of 62

Study of Compounds — Sulphuric Acid — Question 4

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Question 4

State your observation when –

(a) Sugar crystals are added to a hard glass test tube containing conc. sulphuric acid.

(b) Conc. H2SO4 is added to a crystal of hydrated copper sulphate.

Answer

(a) Steam is evolved from the test tube and it becomes very hot. Black spongy mass of carbon is formed.

C12H22O11Cane Sugar (s)→Conc. H2SO412C (s)Sugar Charcoal+11H2O\underset{\text{Cane Sugar}}{\text{C}_{12}\text{H}_{22}\text{O}_{11}} \text{ (s)} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{Sugar Charcoal}}{12\text{C (s)}} + 11\text{H}_2\text{O}

(b) The blue coloured hydrous copper sulphate changes to white anhydrous copper sulphate as the water of crystallization is removed.

CuSO4.5H2O→Conc. H2SO4CuSO4 [White Anhydrous]+5H2O\text{CuSO}_4\text{.5H}_2\text{O} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \text{CuSO}_4 \text{ [White Anhydrous]} + 5\text{H}_2\text{O}