Tuesday, May 14, 2013

Can hydrochloric acid (HCl) act as a buffer in solution?

Yes, solutions of strong acids can act as buffers at pH below 2. This can be seen during a titration experiment of a hydrochloric acid (HCl) solution with sodium hydroxide (NaOH). Let's say we have a 100 ml 0.1 M  HCl solution and is titrated with 0.1 M NaOH solution. The starting pH of HCl solution can be calculated  for 0.1 M solution to be 1. When NaOH is added incrementally to the solution the pH starts to rise as shown in the following titration table:



As seen in the table, after addition of 50 ml of NaOH the pH rose only to 1.48 (0.48 units change). Even after adding 80 ml the pH became 1.95. Thus, strong acids act as buffers at low pH values because their solutions resist pH change upon addition of a base.

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