When salts such as NaCI are added to water, they dissolve and dissociate into io

Question

When salts such as NaCI are added to water, they dissolve and dissociate into ions. NaCI dissolves to Na+ and Cl". Similarly, CH_3NH_3NO-3 is a salt so when it is added to water, it will dissolve and dissociate into ions: CH-3NH_3+ and N0_3-. When these ions are in water, what will happen? Will either ion react with water? NO_3" is the conjugate base of a strong acid, HNO_3 (one of the strong acids from question 3 you have memorized!). As a conjugate base of a strong acid, NO_3" is very weak and stable so NO_3" will not react with water. CH_3NH_3+ is the acid of a weak base, CH3NH2 so it will react with water: What is the pH of a 0.015 M CH_3NH_3NO_3 solution? Kb (CH_3NH_2) = 5.2 times 10^4?

Explanation / Answer

CH3NH3NO3 --> CH3NH3+ + NO3-
CH3NH3+ <--> CH3NH2 + H+

Kb of (CH3NH2) = 5.2 x 10-4
CH3NH2 + H2O <--> CH3NH3+ + OH-
Kb = [CH3NH3+][OH-] / [ CH3NH2]
(5.2 x 10-4) = (0.015 - x) (x) / x
x = 0.01499 = [OH-]
pOH = 1.5
pH = 12.5

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.