Answer:
[tex]0.887[/tex]
Explanation:
Hello,
In this case, the law of mass action for the first reaction turns out:
[tex]Kc=\frac{[AsH_3]^2}{[As]^2[H_2] ^3}=1.27[/tex]
Now, for the second reaction is:
[tex]Kc=\frac{[As][H_2] ^{3/2}}{[AsH_3]}[/tex]
Therefore, by applying square root for the first reaction, one obtains:
[tex]\sqrt{Kc} =\sqrt{\frac{[AsH_3]^2}{[As]^2[H_2] ^3}} =\sqrt{1.27}[/tex]
[tex]\frac{\sqrt{[AsH_3]^2} }{\sqrt{[As]^2} \sqrt{[H_2] ^3} } =\sqrt{1.27}[/tex]
[tex]\sqrt{1.27}=\frac{[AsH_3]}{[As][H_2] ^{3/2}}[/tex]
Finally, since Kc is asked for the inverse reaction, one modifies the previous equation as:
[tex]Kc'=\frac{1}{\sqrt{1.27} }=\frac{[As][H_2] ^{3/2}}{[AsH_3]}=0.887[/tex]
Best regards.
