Question

When a 23.2 mL sample of a 0.345 M aqueous acetic acid solution is titrated with a 0.336 M aqueous sodium hydroxide solution, what is the pH after 35.7 mL of sodium hydroxide have been added? pH =

Answer 1

given acetic acid Sodium Hydroxide. Volume = 23.2ml Volume=) 35.7ml Molarity =) 0.345. Molarity=) 0.336 know that :-) no molarity =) so. M =) n moles volume n =) MVI on (moles of CH₃ COOH 4) 0 =) (0.345) (23-2) nchy CooH =) 8 milli moles anNaOH =) (0.336) (35.7) = 12 m moles So CH₃ COOH + NaOH - CH3COONa+ H₂O t=0 8 12. (no. of milli mole 12-8 8 t=t

So in this weak acid and strong bose titration, acetic acid is limiting is limiting Reagant and consumed Compeletly while Reacting. so Remaining (mmoles) of NooH = 12 - 8 =) u mnoles h Noon =) non fu milli moles Total volume of solution - Vit V2. Vj =) 23.2 + 35.7 =) 58.9 ml [ot] mol 4 in mol =) 0.068 Vol 58.9 me por = -log[on] [log (0.068)] = -(- 1.167 po or - 1.167 we know that pH + por -) 14 (at normal tempo) pH = 14- 1.167 pH = 12.83

2) sa giren HCN VJ 27.6mi M = 0.423M KOH ovy Vkon M = 0.431 為こ)MVO n =) 11.67 are at Equivalence point of titration moles of acid Equal to moles of base So A+ Equivalence Point MHCN = NkoH. =) 11.67 so KOH=) 11.67 = MV VKOH =) 11.67 0.43 1 =) 27.07ml So 27.07 ml of KOH added to get Equivalence Point. now HCN t KOH -) KCN+ H₂O. to 11.67 11.61 11.67 acid and and base both will get completely nuetrolized while Reacting,

+ OH- CNT + HO - HON KCN =) NON =) 11.67 total volume of solution vit V₂ =) V Hent Vroh -) 27.6 + 27.07 Vt =) 54.67m! [(N] =) 11.67 54.67 -) 0.213 CN + H₂O HCN + oH 0.213. ) x 0.213-X. (ka) HEN -) 617x70310 -> according to ICE table and know that Kookb =) kw. Ka = weak acid ionisation constant Ky =) is for base Kw =) Constant for water Kw

х) - ). 6xo) ++o. 3ч хог о к :) kw ka К. :) 1) оке 6. 1 х 10 10. К) 2) 1.6 xos К. Е) 22 -) ). 6x16 5 (o21) - ) 2 к? 1.6 xio Sy-o-3 х о здо So for a quadratic Ear с) - 2.6х16 (6.6xis")" (-озчко) 2. y) - 1. ( x 3.60 x to 1 2. ( x, 1 2. ри) х) 1.83 х10 - Сон ) - lоѕtон) 5 ерн.) -log (7.03xis ен. 2-79 ен, он ч р. - 2.74 он) 1.2 ( ) Eq. Point is 1.2. ен ад