What is the H\" ion concentration in a 2.1 times 10^-2 M KOH solution? A) 4.8 ti

Question

What is the H" ion concentration in a 2.1 times 10^-2 M KOH solution? A) 4.8 times 10^-2 B) 1.0 times 10^-2 M C) 4.8 times 10^-11 M D) 4.8 times 10^-12 M E) 2.1 times 10^-13 M A fruit drink has a pH of about 5.0, while milk has a pH of about 7.0. How many times greater is the H_3O^4 concentration in fruit drink than in milk? A) 2.3 times higher in fruit drink than in milk. B) 100 times higher in fruit drink than in milk. C) 0.43 times higher in fruit drink than in milk. D) 1,000 times higher in fruit drink than in milk. R) 10,000 times higher in fruit drink than in milk. Calculate the pH of a 0.14 M HNO_2 solution that is 14.1% ionized. A) 0.85 B) 1.70 C) 2.10 D) 11.90 E) 13.10 Identify the conjugate base of H_2 PO_4 in the reaction CO_3^2- + H_2PO_4^- HCO_3^- + HPO_4^2- A) H_2O B) HCO_3^- C) H_2CO_3 D) PO_4^3- E) None of these. Which one of the following is a buffer solution? A) 0.40 M HCl and 0.10 MKCI B) 0.20 M CH_3COOH C) 1.0 M HNO_3 AND 1.0 M NaNO_3 D) 0.10 M KCN E) 0.50 M HF and 0.40 NaF When 2.0 times 10^-1 mole of nicotinic acid (a monoprotic acid) is dissolved in 350. mL of water, the pH is 3.50. What is the K_a of nicotinic acid?

Explanation / Answer

Q6.

find [H+] given

[KOH] = 2.1*10^-3 M

[OH-] = [KOH] = 2.1*10^-3 M

Kw = [H+][OH-]

Kw = 10^-14 at 25°C so

10^-14 = ([H+])(2.1*10^-3)

[H+] = (10^-14) / ((2.1*10^-3)) = 4.7619*10^-12 M

best answer is C

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