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1, A 0.50 M solution of an acid is 5.6% dissociated. Determine the pH of the sol

ID: 1034185 • Letter: 1

Question

1, A 0.50 M solution of an acid is 5.6% dissociated. Determine the pH of the solution and the K, for this acid. 2. Consider the following fully deprotonated anions and give the name and formula of the corresponding acid in its fully protonated form: arsenite ion citrate ion azide ion perbromate ion N3 BrO 2. Calculate the pH of the following solutions: (a) 3.5 M sodium fluoride (b) 4.9 ammonium chloride 3. Are aqueous solutions of the following salts acidic, basic or neutral: NaF 4. Consider the images of aqueous solutions of the salts Nax, Nay, and NaZ. (a) Which solution has the highest pH? (b) Which anion, X-, Y-, or Z-, is the strongest base? (c) Which acid, HX, HY, or HZ, is the strongest acid? Ba(NO)2 NH CIO NHAF -HA 5 6 8 Ul

Explanation / Answer

1. A 0.50 M solution of an acid is 5.6% dissociated. Calculate pH of the solution and pka of the acid.

Assume that the acid is HA,

the dissociation of the acid HA would be: HA (aq) <========> H+ (aq) + A- (aq)

Setting up the ICE table: I 0.50 M 0 0

C -x +x     +x   

E 0.50 -x x x

% dissociation = {[H+]equilibrium / [HA]initial}*100

5.6 = (x/0.50)*100 => x = (5.6*0.50)/100 = 0.028

since x= 0.028M,

[H+]equilibrium = 0.028 M, [A-]equilibrium = 0.028 M and [HA]equilibrium = 0.50 -0.028 = 0.472 M

pH = -log[H+] = -log(0.028) = 1.55

ka = {[H+][A-]}/[HA]

ka = (0.028)2/ 0.472 = 1.66 x 10-3