Question

Table 3 (Base Capacity of Buffer Solutions) Volume Total Volume pH NaOH Added NaOH Added (meter) 0.0 mL Initial pH of Buffer 4.53 5.0 mL 5.0 mL 5.0 mL 10.0 mL 10.0 mL 20.0 mL 10.0 mL 30.0 ml 20.0 mL 50.0 mL Part II: Table 2 (Acid Capacity of Buffer Solutions) Volume Total Volume HCL Added HCI Added (meter) 0.0 mL Initial pH of Buffer 4.49 5.0 mL 5.0 mL 4.30 5.0 mL 10.0 mL 4.01 10.0 mL 20.0 mL 3.39 10.0 mL 30.0 mL 1.91 20.0 mL 50.0 mL 1.48 pH

I do not understand how to answer the 2 questions. if someone could answer it and explain, that would be nice. Thank you!

Answer 1

According to defination buffer capacity is defined as the amount of a strong acid or a strong base that has to be added to 1 litre of a buffer to cause pH change by 1.0 pH unit. so buffer capacity can be find by plotting the graph from the given data and mark the volume showing change in pH in acid (buffer pH -1) and base (Buffer pH +1). the respective volume will be buffer capacity of given buffer. Graphs are given below for the provided data.

Buffer pH Buffer pH - 1 Acid Buffer Capacity 10 20 30 50 Volume of HCl added

Buffer pH +1 - - - - - - - - - - ----------- ------- Buffer pH . Base Buffer Capacity 10 20 Volume of NaOH added 30 50