What would you observe in the following cases?
(i) Sulphur trioxide is dissolved in water on a large scale.
(ii) Concentrated sulphuric acid is added to equal volumes of cold water.
(iii) 100 ml of 98% sulphuric acid is kept open.
(iv) Hot concentrated sulphuric acid is added to sodium chloride crystals.
(v) Dilute sulphuric acid is added to ferrous sulphate solution.

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Solution

(i) Sulphuric acid is obtained when sulphur trioxide is dissolved in water on a large scale.
SO₃ + H₂O → H₂SO₄
(ii) When concentrated sulphuric acid is added to an equal volume of water, a large amount of heat is evolved as it is an exothermic process. As a result, the contents of the container may spill out.

(iii) When 100 ml of 98% sulphuric acid is kept open, it absorbs moisture from the air due to its hygroscopic nature. Subsequently, the level of concentrated H₂SO₄ in the container rises.
(iv) When hot concentrated sulphuric acid is added to sodium chloride crystals, sodium hydrogen sulphate is formed.
${NaCl + H}_{2} S O_{4} \overset{{<200}^{0} C}{\to} {NaHSO}_{4} + HCl$
(v) No reaction occurs when dilute sulphuric acid is added to a ferrous sulphate solution.

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Similar questions

Give reasons for the following:
(i) In the contact process, sulphur trioxide formed is dissolved in 98% sulphuric acid and not in water.
(ii) When solution of sulphur dioxide is exposed to air, it gets converted to sulphuric acid.
(iii) When diluting concentrated sulphuric acid, the acid should be added to water and not water to the acid.
(iv) When concentrated sulphuric acid is exposed to air, its volume increases and it becomes slightly dilute.
(v) Sulphuric acid can form two kinds of salts with sodium chloride.
(vi) When barium chloride is added to dilute sulphuric acid, a white precipitate is formed.
(vii) When carbon is heated with concentrated sulphuric acid, carbon dioxide is formed.
(viii) Ammonia gas cannot be dried by passing through concentrated sulphuric acid.
(ix) When concentrated sulphuric acid is added to sugar/glucose, a black mass is left behind.
(x) Concentrated sulphuric acid should not be added to oxalic acid or formic acid in the open laboratory.
(xi) When concentrated sulphuric acid is added to blue crystalline copper sulphate, it turns powdery white.
(xii) Concentrated sulphuric acid must be stored in airtight bottles.
(xiii) Cotton clothes get burnt with concentrated sulphuric acid.
(xiv) H₂SO₄ cannot be prepared by heating sodium sulphate with conc. HCl or HNO₃.

What do you observe when

(a) dilute sulphuric acid is added to granulated zinc ?

(b) a few pieces of iron are dropped in a blute solution of sodium chloride ?

(d) ferrous sulphate solution is added to an aqueous solution of sodium hydroxide.

(e) solid lead nitrate is heated ?

(f) when dilute sulphuric acid is added to barium chloride solution ?

Q. State your observations when:
(i) Dilute hydrochloric acid is added to lead nitrate solution and the mixture is heated.
(ii) Barium chloride solution is mixed with sodium sulphate solution.
(iii) Concentrated sulphuric acid is added to sugar crystals.
(iv) Dilute hydrochloric acid is added to copper carbonate.
(v) Dilute hydrochloric acid is added to sodium thiosulphate.

Q. While preparing dilute sulphuric acid from concentrated sulphuric acid in the laboratory, the concentrated sulphuric acid is added slowly to water with constant stirring. Explain why ?

Why concentrated sulphuric acid is added to water and not the water to concentrated sulphuric acid

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