查看完整版本 : 平衡常數Kc

無奈的決定 2012-6-3 05:10 PM

平衡常數Kc

在1292度,以下反應的平衡常數:
2H2O(g)    ---->/<---   2H2(g) + O2(g)  Kc = 1.60 x 10^-11 mol dm-3
2CO2(g) ---->/<-----  2CO(g) + O2(g)  Kc=1.3x10-10 moldm-3

在相同溫度下,計算以下反應的平衡常數
CO2 + H2 -->/<--  H2O(g) + CO(g)
唔係好明點計,係咪好似赫斯定律咁計?
大家比啲提示就ok:loveliness:

jmlo 2012-6-5 10:08 AM

回覆 1# 的帖子

I adopt the following notations:
2H2O(g)    ---->/<---   2H2(g) + O2(g)  Kc1
2CO2(g) ---->/<-----  2CO(g) + O2(g)  Kc2
Obviously, by definition
Kc1 = p(H2)^2 p(O2)/p(H2O)^2    …… (1)
Kc2 = p(CO)^2 p(O2)/p(CO2)^2    …… (2)
Both (1) and (2) contain p(O2); so we can equate them to obtain
Kc1 p(H2O)^2/p(H2)^2 = Kc2 p(CO2)^2/p(CO)^2
After rearranging the terms, we have
p(H2O)^2 p(CO)^2/p(H2)^2 p(CO2)^2 = Kc2/Kc1   …… (3)

The chemical equation of question is
CO2 + H2 -->/<--  H2O(g) + CO(g)  Kc3
By definition,
Kc3 = p(H2O) p(CO)/p(CO2) p(H2)   ……  (4)

Do you see any similarity between equations (3) and (4) right now? :loveliness:

Zzlaz 2012-6-18 01:21 AM

這是數學遊戲多過化學問題:smile_34:
學校考試會出
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