Calculate Equilibrium constant, if delta Gf for NH3(aq) is -26.50 kj/mole; for H2O(l) is 237.13 kj/mole;for NH4+(aq) is -79.31 kj/mol; for OH-(aq) is 157.3 kj/mole. How many moles of NH4Cl must be added to 1.0L of 0.10M NH3 to make a buffer whose pH is 9.0?