The equilibrium constant at 278 K for
` Cu(s) +2Ag ^(+) (aq) hArr Cu^(2+) (aq) + 2Ag(s)`
is ` 2.0 xx 10^(15) . ` At a particular moment , the concentration of `Cu^(2+) and Ag^(+) ` ions are found to be `1.8 xx 10 ^(-2) " mol " L^(-1) and 3.0 xx 10 ^(-9) " mol " L^(-1)`
respectively . Is the system in equilibrium at that moment?

Answer

A, B

Explanation

Applying the law of chemical equilibrium to the given reaction, we have
`K=([Cu^(2+)(aq)][Ag(s)]^(2))/([Cu(s)][Ag^(o+)(aq)]^(2))`
By convention, putting `[Ag(s)]=1` and `[Cu(s)]=1`
`:. K=([Cu^(2+)(aq)])/([Ag^(o+)(aq)]^(2))`
Putting `[Cu^(2+)]=1.8xx10^(-2) "mol" L^(-1)`
and `[Ag^(o+)]=3.0xx10^(-9) "mol" L^(-1)`
`K=(1.8xx10^(-2))/((3.0xx10^(-9))^(2))=2xx10^(15)`
Which is same as for the reaction in equilibrium. Hence, the given system is in equilibrium.