Question

A.

B.

How many grams of solid ammonium chloride should be added to 1.00 L of a 0.108 Mammonia solution to prepare a buffer with a pH of 9.920 ? grams ammonium chloride = g.

C.

Answer 1

Volume of ammonia solution - 1.000 molarity of ammonia solution 0.108M PH = 9.920 dowi Base dissociation constant (Kg) for anmorng Solution - 1.8x 10 we know that kwa kaxk & Kao Kolk Here, kwa lxlots Ka = Ixlola – 5.55 x 100 1.8x105 dow Pk a = - Log (ka) -- Log (5.55x10o) - Pka = 9.25 dow. using Henderson - Hasselbalch equation FEBase] PH I Prat log Tonjugate acid pH = Pkat Log ( Editi Hyt g.g20 = 9.25 tl o.108 जसकी log(0.1087- Log ([dH4 = 9.9209.25 0.966 - Log([dhu - 0.67 log([d Hut)) = 0.966-0.67 -0.296

. Pka = - Log (ka) - = -log(6.2x10 10) = 9.21 Pka = 9.21 using Henderson - Hasselbalch equation pH = ekat log - Bases [Conjugate acid] pH _pka = log ( [an] CHCA 8.528-9.21 - Log([cd]) - Log ([Hea) - - 0.682 = Log(tar] - log co. 196) -0.682 – Log([ca]-(-0.708) [cd] – -0.68.2 - 0. 708 - 1. 39 [cd] – lots = 6.04lm . concentration of cd or dach = dinul molarity of Nach = 0.041m = 0.04 mille Volume of solution = lol . الیاه ل molarity = moles of dach Volume of solution 0.04 mol - Moles of Naod look moles of Nach = 0.047 mol

1 molar mass of Nacd=49.0 almol SF Nacd - Moles of daca X Molar Mass OF Nach = 0.041 mol X 49 Ilmos = 2.oog g Hence, mass of dach(s) or granis of solid Sodium cyanide (Nach) = 2.005 =/2 og Volume of Solution = l.ol Molarity of ammonia (dHz) solution = 0.138M PH = 8.450 P.ka for animonia.(Hz) Solution = g. 25 dow, using Henderson - Hasselbalch equation PH - Pkat log ([Base] 3 [Consugate acid)) PH - Pka = Logl [HH3) I2H 8.450 9.25 = Log (0-138) -log(CNHS) -0.8 -0.860 - log ([d Hut -

log (ENHA]) = - [NHGT] = -0.860 t o.8 = -0.06 100.06 = 0.87th Concentration of dHJ of moles of Hucl = Molarity of Huct = 0.87 M. Huck X volume of Solution = 0.87 mol x 1.08 = 0.87 mol moles of Huct = 0.87 moi Mass of dHull - Moles of dHlycd xMolar Mass of «Қч с л - 0.87 mod x 53. usiglo mass of dhucd = 46.54 g Hence, grams of solid ammonium chloride (Huch) = 46.54 8 1