Question

One molecule of an oxyacid of sulphur has 3 oxygen atoms. When it reacts with two molecules of KOH, a salt is formed. Calculate the total number of atoms present in 5 molecules of this salt and the number of atoms of each of the constituent elements.

Answer 1

1. Oxy acids of suiphur are sulphuric acid( H₂SO₄) and suphurous acid.(H₂SO₃)
2. The oxyacid of sulphur with 3 oxygen atoms is sulphurous acid..(H₂SO₃).
3. 2KOH (aq) + H₂SO₃(l) $\to$K₂SO₃ (aq) + 2H₂O (l)
4. Atomicity (total number of atoms in one molecule ) of potassium sulphite (K₂ SO₃) is 6 (S=1 , K=2 and O=3. ).

The total number of atoms present in 5 molecules of salt = 5x6 = 30.

The number of atoms present in one molecule of the salt, K$\to$2, S$\to$1, O$\to$3