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Cool goIITian

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13 Sep 2008 17:38:38 IST

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chemical eq

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ammonium carbamate when heated to 473 K, gives mixture of ammonia and carbon dioxide with density of 16. what is the degree of dissociation of ammonium carbamate?

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siddharth89 no longer a school boy ......

Blazing goIITian

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13 Sep 2008 19:10:18 IST

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Ans is 1.4375

Bipin Dubey

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14 Sep 2008 13:43:20 IST

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NH₄NH₂CO₂ = 2NH₃ + CO₂

Initially 1 0 0

Equilibrium 1 - y 2y y

Total moles at equilibrium = 1+2y

mole fraction of ammonium carbamate, x₁ = (1-y) / (1+2y) and its mol wt, M₁ = 78

mole fraction of ammonia, x₂ = 2y / (1+2y) and ts mol wt, M₂ = 17

mole fraction of carbon dioxide, x₃ = y / (1+2y) and its mol wt, M₃ = 44

Average molecular wt of mixture = x₁M₁ + x₂M₂ + x₃M₃ = {78(1-y) + 17(2y) + 44(y)} / (1+2y) = 78/(1+2y)

density is given by, d = PM / RT

16 = (1)(78 / 1+2y) / (0.0821)(473)

Now calculate for y.

siddharth89 no longer a school boy ......

Blazing goIITian

Joined: 28 Feb 2008

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14 Sep 2008 19:47:17 IST

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y is negative according to above solution but degree of dissociation can never be negative

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