How can concentrated Sulphuric acid (H2SO4) burn a hole in a cotton cloth although no water is present there (its concentrated)? acids show acidic properties in the presence of water and we all know that being corrosive is one of the properties of acids

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Solution

Sulphuric acid is a strong dehydrating agent, and converts carbohydrates into simple carbon, a reaction called as carbonization,
conc. H₂SO₄, has a high affinity for H₂O molecules and it degrades carbohydrates as:
n(C₆H₁₀O₅) + H₂SO₄ â†’ 6n C + 5n H₂O
Cotton which contains cellulose in high percentage hence loses its fabric structure and a hole is formed in it.
It is not true that acids need water every time to exhibit their reactivity, though they do need water to form ions.

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Similar questions

(a) Which property of sulphuric acid accounts for its use as a dehydrating agent ?

(b) Concentrated sulphuric acid is both an oxidizing agent and a non-volatile acid. Write on equation each to illustrate the above mentioned properties of sulphuric acid.

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.

(a) Name the process used for the large scale manufacture of sulphuric acid.
(b) Which property of sulphuric acid accounts for its use as a dehydrating agent?
(c) Concentrated sulphuric acid is both an oxidising agent and a non-volatile acid. Write one equation each to illustrate the properties of sulphuric acid mentioned above.

Q. In the presence of concentrated sulphuric acid

(H_{2} S O_{4})

, acetic acid reacts with ethyl alcohol to produce :

(c) (i) Name the process used for the large scale manufacture of sulphuric acid.
(ii) Which property of sulphuric acid accounts for its use as a dehydrating agent?
(iii) Concentrated sulphuric acid is both an oxidizing agent and non-volatile acid. Write one equation each to illustrate the above mentioned properties of sulphuric acid.

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