Question

a) The active ingredient in Aspirin™ is acetylsalicylic acid, HC₉H₇O₄ (K_a = 2.75 x 10^–5). To treat your headache after writing exams, you take two tablets dissolved in 250 mL of water. If each tablet contains 0.32 g acetylsalicylic acid, find the pH of the solution.

Proper pH significant digit is required for full marks.

b)Hydrazine, N₂H₄, is a base in aqueous solution. A 0.20 mol/L solution of hydrazine in water has pH = 10.77. What is K_bfor hydrazine?

Express your answer in the a.b x 10^-c format. abc

c)The two acid ionization constants for oxalic acid, HOOCCOOH, are K_a1 = 5.6 x 10^–2 and

      K_a2 = 1.5 x 10^–4. What is the base dissociation constant, K_b, for OOCCOO^2–(aq)? Express your answer in the a.b x 10^-cd format. abcd

d)Sodium azide, NaN₃(s) has many uses. It is the chemical used to make automobile air bags inflate with N₂(g), and it is sometimes added to water to kill bacteria. What is the pH of a 0.010 mol/L aqueous solution of NaN₃(aq)? Only the azide ion, N₃^–(aq), affects the pH of water. For hydrazoic acid, HN₃(aq), K_a = 1.9 x 10^–5.

Answer 1

Ка (нсан104) = 2.1 x 10 S : "@ve hav4 ) = 6 2 ) ме нса 174 Catho4° 0.32 10 xloro C = CI 2. През 2se- 7 • 1 x-3. Се 2 1:1 хүр-3-х Каа Си*) Сce-4049) Гиси,4 ] x . . 2 5S хіб - *1 xio - x 2 с = 6 2 2.Э ХІь- - (а-1 x102-х ) + 2 - ЭСХjo-S 1.46X10 -4 4. 20. Хіб Vo1 х2 M, Ря: log Сңt) -ls ( ч.25 хув4) p1 3.37 п + ОН ® X . Кь N, 4) = = M ря: |ь: . 2h4 thot Mangt • 20 - I'Nans] Ton) сі [naha) Р*=10*7- - -log Cn-) : Tь- —II Ch+) . 1.1 Хо Com) : = S. 8Хіь 1). Cut) To-10---- ko То: 14 с 1-2 хіргі

aand ке, а = (- sx70-4. from lij х = Cu, s'] = Con:) : 5-89 xt-чга. [,ич 1 - 0:2 - x 6. – 5.83xio 4 О. 20 м. 2 (ska xio -> 5. Ч4 XIO | ь : 3. SXio + - 2 Ка, 56xfo Со 64) к 6 б: ию Р Кь и ) с { би - - - ЕИ,о е по -1 , <a . 1. 40oС-суп +v, o- Қа, Gooc coon & so Ка, 2 Жос-Соти] tso"] Сиоос –ссть) Каъ Goc-coot H₂o corn +,0 S), қау 2 (Soc-com) Спо (80c-coop — сіі) and (6c cool cone) (bdc-cope) (iii , -

kaxkb from ciis and cilj KezxKb = ( BocceGO] [ngot] Poc-coon) Pony Tooc-coon 1oc-cooby [ro] Ton) С. S Kb = lola 10-19 1.5X164 . = 6.7x1014 kaz i's Saul 0.01 M Ka 1.9x105 = 4.72 Ko= 6.781614 [Nans] = Nanla of weak acid (HN₂) and strony base (Noon) so hydrolysis spka of Ngo will take place and a solution become bass c ph 7+ (pleb tlogo) phz7f 7 + (4.72 +log съ2 = 2 0.01 01 c8 2 pn = 8:36