Three 1.00 L buffer solutions are made as follows:
• Buffer 1: 0.050 mol HA and 0.050 mol A⁻
• Buffer 2: 0.100 mol HA and 0.100 mol A⁻
• Buffer 3: 0.100 mol HA and 0.050 mol A⁻
An identical 0.010 mol aliquot of HCl is added to each. Which buffer’s pH will change the least? State the buffer number and give one concise reason.