In what way do ammonia and other ammonia-like molecules (amines) act as bases? a

Question

In what way do ammonia and other ammonia-like molecules (amines) act as bases? a) The lone pair on nitrogen accepts an H+ ion from an acidic molecule. b) They will react with water to generate H+ ions in solution. c) In aqueous solution they produce NH2- ions, which are good proton acceptors. d) They each have hydrogen atoms already, which increase their affinity for another hydrogen. Determine the percent ionization of a 0.120 M HCN solution. Express your answer using two significant figures. Find the pH of a 0.390 M aqueous benzoic acid solution. For benzoic add, Ka = 6.5 times 10-5. Express your answer using two decimal places.

Explanation / Answer

Part A)

correct answer : option a)

Part B)

concentration of HCN = 0.120 M

Ka of HCN = 6.2×10–10

[H+] = sqrt (Ka x C)

       = sqrt (6.2×10–10 x 0.120)

      = 8.63 x 10^-6 M

percent ionization = ([H+] / C ) x 100

                             = ( 8.63 x 10^-6 / 0.120) x 100

percent ionization = 0.0072 %

Part C)

Ka = 6.5 x 10^-5

C = 0.390 M

[H+] = sqrt (6.5 x 10^-5 x 0.390)

       = 5.04 x 10^-3 M

pH = -log (5.04 x 10^-3)

pH = 2.30

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