In water, HCN is a weak acid with pKa= 9.6.
a. Calculate the the Ka and the [H+] in a 0.15 M solution of HCN.
b. In a closed system, these equilibria are established:
HCN(g) s HCN(aq)
HCN(aq) s H+(aq) + CN-(aq)
1) Calculate Kp for the equilibrium between HCN(g) and HCN(aq) at 298 K.
?Gf° kJ.mol-1
HCN(g) 124.7
HCN(aq) 119.7
2) If the total cyanide concentration in solution (i.e. [CN-] + [HCN]) is 0.10M, calculate the partial pressure of HCN(g) in this system at pH = 7.