 You can also make a buffer from a weak base in its conjugate acid. For reference, I have a 0.1 molar solution of ammonia, a weak base. We can see the starting pH is about 11.3 for just a weak base. I have a buffer solution that has 0.1 molar in ammonia and 0.1 molar in ammonium chloride. Notice that the starting pH is lower than the pH of just the 0.1 molar ammonia. We've added some of the conjugate acid so the pH is lower. A solution of a weak base in a conjugate acid also acts as a buffer. If I add some HCl to the buffer, the pH has not changed very much. But after adding 15 drops, the pH has dropped rapidly. We have a new sample of the 0.1 molar ammonia, 0.1 molar ammonium chloride buffer solution. We're going to add some 1 molar sodium hydroxide to the solution. We add 5 drops. The pH has only risen slightly. We're using up the conjugate acid. After about 30 drops, the pH has started to rise significantly.