Q. Which of the following is not a buffer solution?
A) $100\ mL\ 0.1\ M\ CH_{3}COOH + 50\ mL\ 0.1\ M\ CH_{3}COONa$
B) $100\ mL\ 0.1\ M\ CH_{3}COOH + 50\ mL\ 0.1\ M\ NaOH$
C) $50\ mL\ 0.1\ M\ CH_{3}COOH + 100\ mL\ 0.1\ M\ NaOH$
D) $100\ mL\ 0.1\ M\ NH_{4}OH + 50\ mL\ 0.1\ M\ HCl$
Explanation
(c)
Acidic buffer is a mixture of weak acid and its salt with strong base. Similarly, basic buffer is a mixture of weak base and its salt with strong acid. Hence, $50\ mL\ 0.1\ M\ CH_{3}COOH + 100\ mL\ 0.1\ M\ NaOH$ does not constitute a buffer solution because in this case millimoles of acid are less than that of strong base, which after reaction with strong base gives salt. Now, the solution contains only strong base and salt but no weak acid. Hence, no buffer is formed.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.