At $60\,^{\circ}C$,the concentration of $[H_3O^{+}]$ in pure water is $10^{-6.7} \, \text{mol/L}$. What is the value of $K_W$ at $60\,^{\circ}C$?

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

$A$ sample of $MgCO_3$ is dissolved in dil. $HCl$ and the solution is neutralized with ammonia and buffered with $NH_4Cl / NH_4OH$. Disodium hydrogen phosphate reagent is added to the resulting solution. $A$ white precipitate is formed. What is the formula of the precipitate?

$K_a$ for $CH_3COOH$ is $1.9 \times 10^{-5}$. Calculate the $pH$ at the equivalence point in the titration of $0.1 \ M$ $CH_3COOH$ with $0.1 \ M$ $NaOH$.

$A$ certain amount of $H_2CO_3$ and $HCl$ are dissolved to form $1 \ L$ solution. At equilibrium,it is found that the concentrations of $H_2CO_3$ and $CO_3^{2-}$ are $0.1 \ M$ and $0.01 \ M$ respectively. Calculate the $pH$ of the solution. Given that for $H_2CO_3$,$K_{a_1} = 10^{-5}$ and $K_{a_2} = 10^{-8}$.

At $25^{\circ}C$,the dissociation constants of acetic acid and $HCN$ are $1.5 \times 10^{-5}$ and $4.5 \times 10^{-10}$ respectively. What is the equilibrium constant for the following reaction? $(CN^- + CH_3COOH \rightleftharpoons HCN + CH_3COO^-)$