in the presence of NH3, Cu+2 forms the complex ion [Cu(NH3)4]+2. If the equilibrium concentrations of Cu+2 and [Cu(NH3)4]+2 are 1.8x10^-17M and 1.0x10^-3M respectively, in a 1.5 M NH3 solution, calculate the value for the overall formation constant of [Cu(NH3)4]+2.
Cu+2(aq)+ 4NH3(aq)-> [Cu(NH3)4]+2(aq)
Koverall= ?
Is this anything other than substitution of the numbers and punching the calculator?
To find the value for the overall formation constant of [Cu(NH3)4]+2, we can use the concentrations of Cu+2 and [Cu(NH3)4]+2.
The overall formation constant (Koverall) can be calculated using the equation:
Koverall = ([Cu(NH3)4]+2]) / ([Cu+2][NH3]4^4)
Before we substitute the values, we need to convert the concentrations to moles per liter (M).
Given:
[Cu+2] = 1.8x10^-17 M
[Cu(NH3)4]+2] = 1.0x10^-3 M
[NH3] = 1.5 M
Substituting the values into the equation:
Koverall = (1.0x10^-3) / ((1.8x10^-17) * (1.5^4))
Calculating:
Koverall = 1.0x10^-3 / (5.13x10^-30)
Koverall = 1.95x10^26
To calculate the value for the overall formation constant, we first need to set up an expression for the equilibrium constant (K) of the reaction.
Writing out the balanced chemical equation:
Cu+2(aq) + 4NH3(aq) ⇌ [Cu(NH3)4]+2(aq)
The equilibrium constant expression (K) can be written as:
K = [Cu(NH3)4]+2 / ([Cu+2] * [NH3]^4)
Given the equilibrium concentrations of Cu+2 and [Cu(NH3)4]+2, we have:
[Cu+2] = 1.8x10^-17 M
[Cu(NH3)4]+2 = 1.0x10^-3 M
However, we still need to find the concentration of NH3. The problem tells us that the solution is 1.5 M NH3, so we can assume that the concentration of NH3 is 1.5 M.
Substituting the values into the equilibrium constant expression:
K = (1.0x10^-3 M) / ((1.8x10^-17 M) * (1.5 M^4))
Simplifying the expression, we get:
K = (1.0x10^-3 M) / (1.8x10^-17 M * 5.0625 M^4)
K = 1.175 x 10^13 M^-1
So, the overall formation constant of [Cu(NH3)4]+2 is 1.175 x 10^13 M^-1.