Question

3) Determine the pH and the concentration of all species at equilibrium of a 0.045 M solution of the diprotic acid salicylic acid. pKa1 = 3.98 and pKa2 7.65. -

Answer 1

Aas) sale cylic acid is HOGMA coon given pka, = 3.98 Ka, z jó Pkal = 1027 0.000104710855 Constructing ice table foro de reaction: hogha cook th 2000) 2 nocz44 cod I hate Chi talas 0.045 + changerm) -4 Equilibrium (my) 0.045-2 Cao) Stag can)

E The exp445 Po, o ka, ё алом 4: Ка - Сио, М Соб) Смя об Сиос, «Соан) = (x) (1) • o 45-х o - 000 to4 - 12855 - - О: 045-х м“ (@o45 -) o ooo lo4 Э12 855 - 4. Э12 078 47xio — о-обо104712.856 x о. Обо 104 Əlo 366 x - 4. Э12 098 49 xio Хto 6 Bolving for a – о. oogli qo| Ч Thus, at equilibdium, (HO CH4 coon] = 0,045— x = о•o 45 -0. oo allo] = 0. 42 8 8 0949 = 0. 0424ч. Сио си4 (об) = [ Mgot) - - о. Ooail qoly = 0. 00 18 м

9івси. Рая - - 1,6 • 2. 2 3 8 э анxjo 8 Constructing ice table from san 20gelsen: по с. На соб lag 14,0 %) - Ос, касбӣ, 1 Иd log) Thilt o oo all 90/ #x +х o o oo a 901 Change CM) Equili burn o oo 21 90 -х x ow wheo/4x The expression for Kag is given by: Ко, - [6 (месо») (изот) Thoghaceo] 2. 238+ 214xt = (x) (a-oo ti oth) (о. бо ди чај -x) (v (oroo ги 901 +7) - . а 38-2114 sto" a-oo ги90-х) О-оо 21 400 x 472 - О. o0493 87248 xid – 2-838 2114 xidx + о-оожи 10 x + a 3 2H4 xiox — 0 - 00*9+3 89448 xi -o 1+o - Doglu по 3237 – 0-004243 8+a+g xid=0

Solving for my no :23867x108M Thus, at equilibdien, [o Cl Hepcoo] x= 2.23867x1õøn : >2.94xio&M [HOCL14 COD] = 0:00 211901-76 = 0.00 211901 – 0.23867 xios = 0.002118987614 0.00212 M (1301) - 0.0021901+x = 0.00211901 +(223867 X10 = 0.002119032394 = 0.002124 pH = -log (ugot] E-log(0.00211903239) = 2.6738624 = 2.67