Question

A buffer with a pH of 4.07 contains 0.25 M of sodium benzoate and 0.34 M of benzoic acid. What is the concentration of [H,O+] in the solution after the addition of 0.060 mol HCl to a final volume of 1.5 L? Assume that any contribution of HCl to the volume is negligible. [H, 0+= 8.91 x10-5

Answer 1

Phcoona phool & Na phcooh + 150 = Phone +1304 [Phcooo] = 0.25m [Ph.co0H] = 0.34 M pH = 4:07 So pH = pka + log Ph cook] PH = pka + log [Pheoor] m 4:07 = pka + logo m, pka = 4:2 Now final volume of solin. 1.5L So, 000 of moles of Phcoolt present in solu?.0.57 moli i no. of moles of ph cool present in sohn": 0.375 mol After that addition of 0.060 mol HCl occurs.

Now excess amount of not will convert into as dissociated phcool phcode 40 plicoot + ko .. 0.51 on 0:060 start of reaction (moles) end of recetion (moles) 0.315.-200 0.57 Now the concentration of phcoom - 0:315ml? 20:21 mol/ the concentration of phcool = 0.57 mille 20138 mol/ Now, * [phcoon So, concentration of :34:2+log 0:21 14301)= 10-3-94 mold pH = 3.94 ;- [143017-10-3094(M) pH pka + log [Pheooo) 0:38