Question

3. What is the molar concentration of Au (aq) in a saturated solution of AuBrs in pure water at 25 °C? The dissolution reaction is At that temperature the solubility product of AuBrs is 4.0 x 10-36 A) 1.0 x 10-12 mol L- B) 2.0 x 10-18 mol L-1 C) 6.2 x 10-18 mol L-1 D) 6.2 x 10-10 mol L-1 E) 2.5 x 10-9 mol L-1

Answer 1

3)

At equilibrium:

AuBr3 <----> Au3+ + 3 Br-

   s 3s

Ksp = [Au3+][Br-]^3

4*10^-36=(s)*(3s)^3

4*10^-36= 27(s)^4

s = 6.2*10^-10 mol/L

Answer: D