Methylamine, CH₃NH₂, Is a Weak Molecular Base with a Value

Multiple Choice

Methylamine, CH₃NH₂, is a weak molecular base with a value of 4.4 × 10^-4 for K_b. An aqueous solution contains 0.200 M CH₃NH₂ and 0.300 M CH₃NH₃Cl per liter as the only solutes. If the K_sp of Fe(OH) ₂ is 7.9 × 10^-16, what is the maximum [Fe²⁺] that can coexist with these solutes in the solution?Hint: Use the Henderson-Hasselbalch formula to find the pOH of the solution, and then use that to find [OH^-].

A) 1.8 × 10^-12
B) 9.0 × 10^-12
C) 1.8 × 10^-9
D) 9.2 × 10^-9
E) 9.2 × 10^-6