We were given concentration and volume of a weak acid and were asked to determine dissociation constant of weak acid, in second problem we were asked to find concentration of each species in solution.
1. One mole of a weak acid is dissolved in 2.0 L of solution (assume that the solution is water). After the system had come to equilibrium, the concentration of HA was found to be 0.45 M. Compute Ka for HA.
2. A solution is made by mixing 500.0 mL of 4.0 M NH3 and 500.0 mL of 0.40 M AgNO3. Ag+ reacts with NH3 to form AgNH3+ and Ag(NH3)2+ according to the equilibrium reactions:
Ag+ + NH3 ↔ AgNH3+ K1 = 2.1 x 103
AgNH3+ + NH3 ↔ Ag(NH3)2+ K2 = 8.2 x 103
Assuming no change in volume on mixing find out the concentrations of all species in solution: [Ag+], [NO3-], [NH3], [AgNH3+] and [Ag(NH3)2+].