Penultimate Problem Set

Monday, Dec. $11$

This problem set is due at $10$ am on Friday, Dec. $8,2023.$

Calculate the $pH$ of each of the following aqueous solutions of acid or base when equilib$-$

rium has been reached. All of the molarities indicated below refer to the Initial conditions.

a$.0\mathrm{.}15MHN{O}_3$

b$.1\mathrm{.}0$mol of solid $Ba(OH{)}_2$ placed into $1\mathrm{.}0L$ of water of barium hydroxide is

$5\mathrm{.}0{10}^{-3})$

c$.14\mathrm{.}0mg$ of NaOH dissolved in enough water to make $255mL$ of solution

d$.0\mathrm{.}150MHF(K_a=6\mathrm{.}6{10}^{-4})$

e$.0\mathrm{.}200M$ ethylamine $(K_b=6\mathrm{.}4{10}^{-4})$; this compound is similar to ammonia, with

$C{H}_{3}C{H}_2$ substituted for one of the hydrogens. Ethylamine is a weak base like ammonia.

A $2\mathrm{.}000-L$ solution was made by dissolving $0\mathrm{.}0100$mol benzoic acid in water. The $pH$ at

equilibrium was measured to be $3\mathrm{.}093.$ Determine the value of $K_a$ for benzoic acid.

Calculate the number of moles of $($undissociated$)HF(K_a=6\mathrm{.}6{10}^{-4})$ present at

equilibrium in a $0\mathrm{.}200-L$ aqueous solution if the measured $pH$ is $3\mathrm{.}25$ at equilibrium.