Given 125 mL of a solution that is 0.0500 M CH3NH2 and 0.0500 M CH3NH3+Cl?, Part

Question

Given 125 mL of a solution that is 0.0500 M CH3NH2 and 0.0500 M CH3NH3+Cl?,

Part A

Over what pH range will this solution be an effective buffer?

Express your answer using two decimal places. Enter your answers as the minimum and maximum pH separated by a comma.

Part B

What is the buffer capacity of this solution? That is, how many millimoles of strong acid or strong base can be added to this solution before any significant change in pH occurs?

Express your answer to three significant figures and include the appropriate units.

Explanation / Answer

pKb of methyl amine = 3.36

so th pH rang is 4.36 - 2.26

Part B

pOH = pkb + log [Salt / base] = 3.34 + log (0.05 / 0.05) = 3.34

OH- = 4.4 X 10^-4

Buffer capacity = C X Kb [OH-] / ( Kb + OH- )2

Kb = 4.4 X 10-4

buffer capacity = (0.05+0.05) X 4.4 X 10^-4 X 4.4 X 10^-4 / (4.4 X 10^-4 + 4.4 X 10^-4 )2

Buffer capacity = 0.1 / 4 = 0.025

.

Related Questions

Navigate

• Browse (All)
• Browse G
• Subjects

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