Video summaries: Buffers solution pH calculation

The following problem is “if 0.03 mol of HCl added to 0.50 L of the buffer solution (0.24 M NH3 and 0.20 M NH4Cl), what is the resulting pH?”. In this case, we have to deal with an acid, we calculate the concentration of HCl 0.03 mol/0.50 L= 0.06 M, and since HCl is a strong acid then we’ll have that the concentration of H3O+ is 0.06 M. And because now we are working with an acid it’s going to react with our base that’s NH3.