Question

In an experiment, 400 mL of each solution is taken, and 0.00900 mol of HCℓ is added to each. Match the descriptions below with the correct values that apply after the addition of HCℓ to these two buffer samples.

	Buffer 1	Buffer 2
CH3COOH present	0.450 mol	0.00450 mol
CH3COO- present	0.450 mol	0.00450 mol
pH	4.74	4.74

Is Buffer 1 still a functional buffer after addition of HCl? Yes or no?

mol of acetate remaining in Buffer 2 after addition of HCl ?

Is Buffer 2 still a functional buffer after addition of HCl?

mol of acetate remaining in Buffer 1 after addition of HCl?

mol of acetic acid remaining in Buffer 2 after addition of HCl?

mol of acetic acid remaining in Buffer 1 after addition of HCl?

Answer 1

More concentrated buffers are better buffers as they can withstand/resist the changes in pH by addition of acid / base.

1) buffer 1 is still a functional buffer after additon of HCl

HA --------------> A- + H+

0.45 0.45 0 initial

- - 0.009 change

0.459 0.441 - after BUffer 1

NOw in buffer 2

   HA --------------> A- + H+

0.0045 0.0045 0 initial

- - 0.009 change

0.009 0.0 0.0045 - after BUffer 1

This is not a buffer as [conjugate base] = 0

2)mmoles of acetate ain buffer 2 after HCl addition =0

3) No

4)moles of acetate in buffer 1after aditionof HCl =0.441

5) mol of acetic acid in buffer 2 after addition of HCl =0.009

6) moles of acetic acid in buffer 1 after HCl addition = 0.459