chem mc 1條

[匿名]

2012-08-17 2:51 am

1.consider the following reaction:
2CH4<------------>C2H2+3H2 where Kc=2.80
initially, 0.4 mole of each substance is placed in a 1.00 dm3 container. which of the following correctly describes this system as it approaches equilibrium?

-------------[C2H2]----------------------rate of forward reaction
A.-------increases-----------------------decreases
B.-------increases-----------------------increases
C.-------decreases----------------------decreases
D.-------decreases-----------------------increases

麻煩解釋。

回答 (1)

己式庚辛

2012-08-18 1:30 am

✔ 最佳答案

Initial conc. of each reactant = 0.4/1 = 0.4M

Initially, reaction quotient, Q = [C2H2] x [H2]^3 / [CH4]^2
= 0.4 x (0.4)^3 / (0.4)^2 = 0.16 M^2
which is lower than Kc of reaction.

That means, more product will be produced by forward reaction when approaching equilibrium, such that reaction quotient will increase and reach the value of Kc.

[C2H2] will increase.

And, Rate of forward reaction at initial state is highest (due to highest conc. of reactants); rate will decrease as conc. of reactant decreases.

Choose A.

👍 0 👎 0