Question

. 20.0 mL of 0.100 M lactic acid solution is titrated with 0.100 M NaOH solution. Calculate the pH of the contents of the Erlenmeyer flask at each of the following points during the titration. (a) When 0.00 mL of NaOH have been added. (2) (b) After 5.00 mL of NaOH have been added. (3) (c) After 20.0 mL of NaOH have been added. (3) (d) After 10.0 mL of NaOH have been added. (1) (e) After 25.0 mL of NaOH have been added. (2) (f) A buffer solution exists in the flask after 5.00 mL of NaOH have been added. Write equations to show the action of the relevant component of the buffer, when acid (H3O+), or base (OH- ), is added from an external source.

Answer 1

PAGE No DATE : 홑 1201 the (a)-- 11 No.-0 lactic acid ?nㅢhe Solution vclume ml) 2 2o 0.1 M -log o.i PH No. ol mmeles o lactic acid 2o x 02 mm hon "Total volume ol. 4ke Solu hon 즈 Volunu ol, acid-na on

PAGE No DATE: 0 SLm 25 acad tibuo th soluba 0.06 moiu (e) 20 ml cL Dim acid + 20mL С О.IM.NO2H andth PH (d) 20 mL NooHu act as imilin otally consumed wrac on Concenteation

PAGE Ho DATE: 1 120 2omL oIM acid 2s mL obo.im Noon acic acid will be acling as umiting ogent ihat u to atteu oddttothe acid Soluh 2.S-2 Total volume20S+20+10+ 2S Concentration eb or-o 0.00625-1 8o -t loq (o 00 62s) iq-(+2,2

DATE : 1 120 In thu seachon s mmoles of lactic oddli thon atcei tThe一ㄧ xtuxe -. Contain-to clie-aad--(HA)-as Let uh Cokide butg T Su acton tha ppose strone aud w oddid The Ht by lackats ons to uocratia HA RAV H30 HA Ho Ho lactate on lachc oud vetchng in PH

O. (ii)一lchen a base (OH) is added the CH H o OH Он 0 Tactate 1で八 lactic acrd agci 따 should be clear trom-the above nothansn- otic acid sodiun lactale butbu to-presence due to os-Lactate-inn