Question

how to find the volume 0.01MHA used and 0.01M NaA used in ml?

Target pH of buffer solution to be prepared 9.24 K = 3.65 x 100 Average value of K (average of the three K, values above) (HA) in buffer R 1.018 [A-] Hint: use Equation (15) Volume 0.10 M HA 1.018 Volume 0.10 M NA needed in buffer Volume 0.10 M HA used 95 mL Volume 0.10 M NaA used ml Measured pH of prepared buffer 9.57 (4.9x10-10) + (5.84 10-10) (6.17*18-10) 15.65 x 10-10 . Average value of Ka [HAin buffer : CH"). Ka x CHAD pH -log[H] [H]. 104.5+ , 5.75 x 10-16 LAJ

Answer 1

Solution:

pH of the buffer is calculated by Hendersen equation as,

pH = pka + log [A-] / [HA]

Total volume = 1L = 1000 mL

The calculated ratio,

[HA] /[A-] = 1.018

[HA] = 1.018 [A-]

Thus,

If [HA] = 1.00, then [A-] = 1.018

Thus,

Total moles per liter = 1.018 + 1.00 = 2.018 mol

Hence,

Volume of HA = (moles of HA / total moles) x 1000 mL

= (1.018 /2.018) x 1000 mL = 504.46 mL

Volume of A- = (moles of A-/ total moles) x 1000 mL

= (1.00 / 2.018) x 1000 mL = 495.54 mL