Question

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A buffer that contains 0.388 M base, B, and 0.283 M of its conjugate acid, BH⁺, has a pH of 8.99. What is the pH after 0.0020 mol of HCl is added to 0.250 L of this solution?

pH =

Answer 1

Buffer solution The pH of a butter solution can be calulares by using the Henderson - Hasselbalch equation, jot = pka + log [ Base] Eacid] t Base] = concentration of base. [Aud] conentration at ka = Acid dissociation constant Pra, - B +H BH Base conjugate auld [B]: 0.388 CBH 0.283 m According to Henderson Hasselbalch equation, pH = pra +log [ B] ) 7 - i EBHD 8.99 - pka tlog ( 388 8.99 - pka + 0.13704 pka = 8.8529 pra value of confugate acid of 'B' 0.283 pH-8-994 How moles of 'B' 8-8529 in 0.250L of 0.388 m 0.388 mole Solution and 1 x 0.250L moles of Solution, 0.097 mole BH in 0.250 L of 0.283 mole. 0.283m 12 8:2501 = 0.07075 mole e added = 0,002 omal

Now, dissociation considend as equilibrium can be ICE table B &H BH Initial , 0.097 0.0020 Change - - 0.0020 -0.0020 Eauilibriums 0.095 0.0 70 75 + 0.0020 0.07275 According Now, 0.095 mole 0.250 L and [BH] = 0.07275 - 0.250 L to Henderson - Hasselbalch equation, pagka tog [ B] [BH+] more 10.095 9 =) pH = 8.8529 + 10g 601250) pH, 8.81529 +0.1158 pH = 8.9687 0.275 10-25 in The ph value after addition of stee 8.9687