Consider a 020 M NH3020M NH4Cl buffer 0001500mol of HCl is a

Consider a 0.20 M NH3/0.20M NH4Cl buffer 0.001500mol of HCl is added to 65.0mL of the bufer. How many moles of NH3 and NH+4 remain once the solution has equilibrated? The Ka for the equilbrium is 5.6x10^-10?

Solution

moles of NH3 initially = 0.20 x 0.065 = 0.013 moles

moles of NH4Cl initially = 0.20 x 0.065 = 0.013 moles

moles of HCl added = 0.001500

Thus, moles of NH3 left = 0.013 - 0.001500 = 0.0115 moles

moles of NH4Cl left = 0.013 + 0.001500 = 0.0145 moles