Question

Sulphide ion in alkaline solution reacts with solid sulphur to form polysulphide ions having formula, \[\ce{S^{2-}2}\], \[\ce{S^{2-}3}\], \[\ce{S^{2-}4}\], etc. if K₁ = 12 for \[\ce{S + S^{2-} <=> S^{2-}2}\] and K₂ = 132 for \[\ce{2S + S^{2-} <=> S^{2-}3}\], K₃ = ______ for \[\ce{S + S^{2-}2 <=> S^{2-}3}\].

विकल्प

• 7

• 11

• 21

• 30

Answer 1

Sulphide ion in alkaline solution reacts with solid sulphur to form polysulphide ions having formula, \[\ce{S^{2-}2}\], \[\ce{S^{2-}3}\], \[\ce{S^{2-}4}\], etc. if K₁ = 12 for \[\ce{S + S^{2-} <=> S^{2-}2}\] and K₂ = 132 for \[\ce{2S + S^{2-} <=> S^{2-}3}\], K₃ = 11 for \[\ce{S + S^{2-}2 <=> S^{2-}3}\].

Explanation:

\[\ce{S + S^{2-} <=> S^{2-}2}\] K₁ = 12 .....(1)

\[\ce{2S + S^{2-} <=> S^{2-}3}\] K₂ = 132 .....(2)

\[\ce{S + S^{2-}2 <=> S^{2-}3}\] K₃ = ?

K₁ = `(("S"_2^(2-)))/(("S") xx ("S"^(2-)))`

Dividing equation (2) by (1)

= `"K"_2/"K"_1 = (("S"_3^(2-)))/(("S")^2 xx ("S"^(2-))) xx (("S")("S"^(-2)))/(("S"_2^(2-)))`

K₃ = `(("S"_3^(2-)))/(("S"^2) xx ("S"_2^(2-))) = "K"_2/"K"_1 = (("S"_3^(2-)))/(("S") xx ("S"_2^(2-)))`

K₃ = `(("S"_3^(2-)))/(("S") xx ("S"_2^(2-))) = 132/12 = 11`