NCERT Class XI Chemistry Equilibrium Solutions

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Question : 17
Total: 73
Kp = 0.04 atm at 899 K for the equilibrium shown below. What is the equilibrium concentration of C2H6 when it is placed in a flask at 4.0 atm pressure and allowed to come to equilibrium?
C2H6(g)C2H4(g)+H2(g)
Solution:  
C2H6(g)C2H4(g)+H2(g)
Initialpressure4.0atm00
At.eqm.4ppp

Applying law of chemical equilibrium,
Kp =
pC2H4×pH2
pC2H6
⇒ 0.041 =
p2
4p
or , p2 = 0.16 – 0.04p or p2 + 0.04p – 0.16 = 0
∴ p =
0.04±0.00164(0.16)
2
=
0.04±0.80
2

Taking positive value, p =
0.76
2
= 0.38
[C2H6]eq = 4 - 0.38 atm = 3.62 atm
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