Ni2 + (aq) + 6 NH3 (aq) ⇌ Ni (NH3) 6 2 + (aq)

is Kf = 5.6 * 108 at 25°C.

(a) What is ΔG o

at this temperature?

(b) If standard-state concentrations of reactants and products are mixed, in which

direction does the reaction proceed?

(c) Determine ΔG when [Ni (NH3) 62+] = 0.010 M, [Ni2+] = 0.0010 M, and [NH3] = 0.0050 M. In which direction will the reaction proceed to achieve equilibrium?

a) ΔGº = - 49,9 KJ/mol = - 50 KJ/mol

b) The reaction goes to the right to formation of products

c) ΔG = 84,42 KJ/mol. The direction is to reactive, to the left

Explanation:

a) ΔGº = - RTLnKf

You need to convert Cº to K. 25ºC=298K

Then, ΔGº = - 3,814 J/molK * 298K * Ln (5.6 * 10^8) = - 49906 J/mol = - 49,9 KJ/mol = - 50 KJ/mol

b) The ΔGº < 0, that means the direct reaction is spontaneous when te reactive and products are in standard state. In other words the reaction goes to the right, to formation of products

c) The general ecuation for chemical reaction is aA + bB → cD + dD. Thus

ΔG=ΔGº + RTLn (([C]^c*[D]^d) / [A]^a*[B]^b)

In this case,

ΔG=ΔGº + RTLn ([Ni (NH3) 62+] / [Ni2+]*[NH3]^6) = 84417 J/mol = 84,42 KJ/mol

ΔG >0 means the reaction isn't spontaneous in the direction of the products. Therefore the direction is to reactive, to the left