Answer to Question #73916 in Organic Chemistry for Audrey Minix

Question

Write the expression for Q in terms of the activities (the [ ] symbols) of the species responsible for driving the reaction to equilibrium:

2Cu^2+(aq)+4I^-(s)=2CuI(s)+I2(s)

Answer 1

2Cu^2+(aq)+4I^-(s)=2CuI(s)+I2(s)
aA+bB⇌cC+dD
The reaction quotient, Q, takes the following form:
Q= ([C]^c [D]^d)/([A]^a [B]^b )
Note that the reaction quotient takes the exact same form as the equilibrium constant, and is a function of concentrations and/or activities of the reactants and products. The difference is that Q applies when the reaction is at non-equilibrium conditions, and therefore its value can vary.
Q=([CuI]^2 [I_2])/([Cu]^2 [aq] [I]^4 )
As a result, the activity, or ideal concentration, of a liquid or a solid is defined as 1.
Q=1/[Cu]^2