Question

Which of the following mixtures would result in buffered solutions when 1.0 l of each of the two solutions are mixed?

a. 0.1 m koh and 0.1 m ch3nh3cl
b. 0.1 m koh and 0.2 m ch3nh2
c. 0.2 m koh and 0.1 m ch3nh3cl
d. 0.1 m koh and 0.2 m ch3nh3cl

Answer 1

A buffered solution typically contains equal molar concentrations of a weak acid and its conjugate base or vice versa. The correct option that would result in a buffered solution is option (a), mixing 0.1 M KOH with 0.1 M CH3NH3Cl, both a strong base and the salt of a weak base respectively.

Step-by-step explanation:

The question concerns the formation of buffered solutions when two different solutions are mixed. A buffered solution can resist changes in pH upon the addition of small amounts of acid or base. To form a buffer solution, we need a mixture of a weak acid and its conjugate base, or a weak base and its conjugate acid. In the options provided:

• Option (a) combines a strong base (KOH) with the salt of a weak base (CH3NH3Cl), which would form a buffer.
• Option (b) is not correct because CH3NH2 is a weak base and will not form a buffer with another base (KOH).
• Option (c) involves larger amounts of the strong base than the salt, which likely won't result in a buffer.
• Option (d) includes a higher concentration of the conjugate acid (CH3NH3Cl) compared to the base (KOH), which could potentially buffer the solution but might not be at equal concentration.

The correct answer is an option (a), as the 0.1 M KOH (a strong base) and the 0.1 M CH3NH3Cl (the salt of the weak base CH3NH2) are in equal molar amounts which is suitable for creating a buffer solution.