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etermine the ammonia concentration of an aqueous solution that has a pH of 11 he

ID: 587160 • Letter: E

Question

etermine the ammonia concentration of an aqueous solution that has a pH of 11 he dissociation of NH3 (Kb = 1.8 × 10-5) is NH3(a) H20()NH4 (aa)+ OH-(aq) (0.056 M) Calculate the pH of a 0.020 M carbonic acid solution, H2CO3(a), that has the s stants Kal-4.3x 10-7 and Ka2 = 5.6 × 10-11 . 36. What is the pH of a 0.20 M solution of NHC1 [KbNHs)-1.8 x 10 ] 37. Which one of these salts will form a basic solution upon dissolving in wate (pH 4.03) A) NaCl B) NaNO2 C) NH4NO3 D) KBr E) AlCl3 Write the reaction of these compounds with water. Which one of the following tion in water? Why? A) NH4Cl

Explanation / Answer

What is the pH of a 0.020 M solution of NH4Cl? [Kb(NH3)= 1.8 * 10^-5]

NH4Cl(aq) ---------------------------> NH4^+ (aq) + Cl^- (aq)

0.02M                                               0.02M

cationic hydrolic is takes place

NH4^+ (aq) + H2O ---------------------> NH3(aq) + H3O^+

I                    0.02                                                    0                  0

C                 -x                                                        +x                   +x

E                 0.02-x                                                    +x                  +x

                       Kb   = 1.8*10^-5

                       Ka   = Kw/Kb

                               = 1*10^-14/1.8*10^-5   = 5.6*10^-10

                Ka   = [NH3][H3O^+]/[NH4^+]

               5.6*10^-10    = x*x/0.02-x

               5.6*10^-10 *(0.02-x)   = x^2

                    x   = 3.35*10^-6

            [H3O^+]    = x = 3.35*10^-6M

            PH   = -log[H3O^+]

                    = -log3.35*10^-6

                    = 5.4749 >>>>>answer