In which of the following mixed aqueous solut | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(D) The $pH$ of an acidic buffer solution is given by the Henderson-Hasselbalch equation:$pH = pK_{a} + \log \frac{[salt]}{[acid]}$For $pH = pK_{a}$,w

Vedclass · Accepted Answer

Both $(1)$ and $(2)$ are correct

Vedclass · Answer

(D) The $pH$ of an acidic buffer solution is given by the Henderson-Hasselbalch equation:$pH = pK_{a} + \log \frac{[salt]}{[acid]}$For $pH = pK_{a}$,we must have $\log \frac{[salt]}{[acid]} = 0$,which implies $[salt] = [acid]$.$(1)$ $100 \ mL$ of $0.1 \ M \ CH_{3}COOH$ $(10 \ mmol)$ + $100 \ mL$ of $0.1 \ M \ CH_{3}COONa$ $(10 \ mmol)$.Here,$[salt] = [acid] = 10 \ mmol$. Thus,$pH = pK_{a} + \log(1) = pK_{a}$.$(2)$ $100 \ mL$ of $0.1 \ M \ CH_{3}COOH$ $(10 \ mmol)$ + $50 \ mL$ of $0.1 \ M \ NaOH$ $(5 \ mmol)$.The reaction is: $CH_{3}COOH + NaOH \rightarrow CH_{3}COONa + H_{2}O$.Initial: $10 \ mmol \ CH_{3}COOH, 5 \ mmol \ NaOH$.Final: $5 \ mmol \ CH_{3}COOH, 5 \ mmol \ CH_{3}COONa$.Since $[salt] = [acid] = 5 \ mmol$,$pH = pK_{a} + \log(1) = pK_{a}$.$(3)$ $100 \ mL$ of $0.1 \ M \ CH_{3}COOH$ $(10 \ mmol)$ + $100 \ mL$ of $0.1 \ M \ NaOH$ $(10 \ mmol)$.This results in complete neutralization to form $CH_{3}COONa$. No buffer is formed.$(4)$ $CH_{3}COOH + NH_{3} \rightarrow CH_{3}COONH_{4}$.This forms a salt of a weak acid and a weak base,not a buffer solution.Therefore,both $(1)$ and $(2)$ satisfy the condition $pH = pK_{a}$.

Similar Questions

The hydrogen ion concentration of a $0.1 \ N$ solution of $CH_3COOH$,which is $30 \%$ dissociated,is (in $M$)

The pairs of compounds which cannot exist together in aqueous solution are :
$I. NaH_2PO_4$ and $Na_2CO_3$ $II. Na_2CO_3$ and $NaHCO_3$
$III. NaOH$ and $NaH_2PO_4$ $IV. NaHCO_3$ and $NaOH$

In which case is the change in $pH$ maximum?

The ionization constant of dimethylamine is $5.4 \times 10^{-4}$. Calculate its degree of ionization in its $0.02 \ M$ solution. What percentage of dimethylamine is ionized if the solution is also $0.1 \ M$ in $NaOH$?

Vedclass Test Series

Exam Paper Generator

Online Exam Module