What is the Keq ? ?

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1 Answer
Apr 25, 2018

#sf(K=2.2xx10^6)#

Explanation:

We can reverse both equations then add:

#sf(Cu(NH_3)_4^(2+)rightleftharpoonsCu^(2+)+4NH_3)#

#sf(K_1=1/K_(f)=1/(2.1xx10^(13))=0.476xx10^(-13))#

#sf(Cu^(2+)+2OH^(-)rightleftharpoonsCu(OH)_2)#

#sf(K_2=1/K_(sp)=1/(2.2xx10^(-20))=0.4545xx10^(20))#

Adding the two equations give us the one we want:

#sf(Cu(NH_3)_4^(2+)+cancel(Cu^(2+))+2OH^(-)rightleftharpoonscancel(Cu^(2+))+4NH_3+Cu(OH)_2)#

For which we can say:

#sf(K=K_1xxK_2=0.476xx10^(-13)xx0.4545xx10^(20)=2.16xx10^(6))#