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Grade 12Physical Chemistry

200 gm of CaCO3 (s) taken in 4 Litre container at a certain temperature. Kc for the dissociation of CaCO3 at this temperature is found to be 1/4 mole litre-1 , then the concentration of CaO in mole/litre is : [Given : CaO = 1.12 gm cm-3 ] [Ca = 40, O = 16]
(A) 1/2 (B) 1/4 (C) 0.02 (D) 20

Profile image of mike
9 Years agoGrade 12
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1 Answer

Profile image of varun
9 Years ago
HELLO,
the reaction is -
CaCO3(s)-----------> CaO(s) + CO2(g)
Kc = [CaO] [CO]
       -------------------
         [CaCO3]
But CaO and CaCO3 are in solid state so concentration of both are taken as unity
therefore,
Kc = [CO2]
but Kc = ¼
therefore,       [CO2] = 1/4
As in the reaction first step reaction we see that 1 mole of CaCO3 will produce 1 moles of CaO and CO2
THEREFORE,
[CaO] = [CO2]
[CaO] = ¼ 
so 1/4 or 0.25 is the answer
THANK YOU