Question

Please answer 18 and 19! and show work

What are the Bronsted-Lowry acids in the following chemical reaction? HBr(aq) + CH_3COOH (aq) CH_3C (OH)^+_2 (aq) + Br^-(aq) a) CH_3COOH, CH_3C (OH)^+_2 b) CH_3COOH, Br^- c) HBr, CH_3COOH d) HBr, CH_3C(OH)^+_2 What is the strongest acid among the following? a) H_2SO_3 b) H_2SeO_3 c) H_2SO_4 d) H_2SeO_4 What is the K_w of pure water at 50.0 degree C, if the pH is 6.630? a) There is not enough information to calculate the Kw. b) 5.50 times 10^-14 c) 1.00 times 10^-14 d) 2.13 times 10^-14 e) 2.34 times 10^-7 Calculate the concentration of H_3O^+ in a solution that contains 5.5 times 10^-5 s M OH^-at 25 degree C. Identify the solution as acidic, basic, or neutral. a) 9.2 times 10^-1 M, acidic b) 1.8 times 10^-10 M, basic c) 1.8 times 10^-10 M, acidic d) 5.5 times 10^-10 M, neutral e) 9.2 times 10^-1 M, basic

Answer 1

18)

pH = 6.630

use:

pH = -log [H3O+]

6.630 = -log [H3O+]

[H3O+] = 2.344*10^-7 M

SINCE water is neutral,

[OH-] = [H3O+]

So,

[OH-] = 2.344*10^-7 M

Now use:

Kw = [H+] [OH-]

= (2.344*10^-7)*(2.344*10^-7)

= 5.50*10^-14

Answer: b

19)

use:

[H3O+] = (1.0*10^-14)/[OH-]

= (1.0*10^-14) / (5.5*10^-5)

= 1.8*10^-10 M

Since [OH-] > [H+], it is basic

Answer: b