Define buffer capacity. Buffer capacity is the amount of base that can be added to change the buffer's pH by 2 Buffer capacity is the amount of acid that can be added to change the buffer's pH by 1 Buffer capacity is the amount of acid or base that can be added to change the buffer's pH by 1 Buffer capacity is the amount of base that can be added to change the buffer's pH by 3 Buffer capacity is the amount of acid that can be added to change the buffer's pH by 2