Question

A) What is the pH at the equivalence point in the titration of a 24.3 mL sample of a 0.333 M aqueous hydrofluoric acid solution with a 0.425 M aqueous barium hydroxide solution?
pH =

B) How many grams of solid sodium hypochlorite should be added to 1.00 L of a 0.206 M hypochlorous acid solution to prepare a buffer with a pH of 8.373
grams sodium hypochlorite = g.

C) How many grams of solid potassium fluoride should be added to 1.00 L of a 0.146 M hydrofluoric acid solution to prepare a buffer with a pH of 2.556 ?
grams potassium fluoride = g.

Answer 1

Salution A 24 3 ml. volume of 0.33m HF concentration = 0.425 m Balon, Bq²+ + 2F By (Onla 2 HF + 2ot Volume malasityx moles of nf= 0.33 MX 24.3 me 8.099 mmolo reaction from the stichiomething meles of Bolon) 2 I x males of nf = moles of Balon), x 8.099 mmal Molarity x valume 4.04959 mmal 0.425 mx v yo04959 v 9.520 ml Volume of Balon used V = 9.53 ml 33.83 nel Tohl volume 9.53 + 24:35 moles of F formed males of dif mmal. q.org

Ге] = males volume — 8.ogg mmal 3.2.3 m - о: 23 99 м C 2 4. Uf = 3. ) 1 Ол ерivsloых раіль и зіrѕ ha ри = + + pka -+ Oез с PR4 +1 хэм + 2 (а-1991) р= + 1 565 + + (-o-baos ) ph pha - 525 б• 3)ОЧ РИ - 4. 27 В 7. 5 ? ipka [naceo Гиао) %: 333 E4:51+ 3 Inaceo Hypochlorous acid (heo) - С. 206 1 ри: 8:3} ? и0 — РИ - РЕ+ log о: 206

0.843. = ley [naceo 0.206 (Na Uo] 0.843 lo 6.966 0.206 (Nq40] = 1.435 M Volume of buffer - mely (Na) - Malasityx volume 1.435 mx lol = 1.435 mol Molor mass of Naceo 7444 g/mal mass of Nade male x molar mass = 1.435 mol X 74.449 mol 106.925 g Theorefore grams of Sedium Hypochlorite 106.925g phz pka + long Igelt] (acid] pra fnf= 3.1.7 ри = 2:556

2.556 3.17 + log [sala] 0.146 - 0.614 10 [sult] Co.146] E 0.2432 [salt 0.0355 M [ kf] 0.0355 M malar mass of Rf=58.096 Ilmal. males of KF Malarity x volume = 0.0355 mxIL = 0.0355 modo goom of KF = 0.0355 X 58.0 96 2.063 g