Post Lab Problems

Gyclohexanol, $C_6{H}_{11}OH,$ is sometimes used as the solvent in molecular weight determinations by freezing$-$point depression. If $0\mathrm{.}253g$ of benzoic acid, $C_6{H}_5\frac{C}{O}OH,$ dissolved in $12\mathrm{.}45g$ of cyclohexanol, lowered the freezing$-$point of pure cyclohexanol by $6\mathrm{.}55C,$ what is the molal freezing$-$point constant of this solvent?

Since the freezing point of a solution depends on the relative number of particles, what would you calculate to be the freezing point of $0\mathrm{.}1m$ solutions in water of $($a$)$ NaCl, $($b$)BaC{l}_2?$ Assume that these salts are $100\%$ Ionized in solution. $($Compare your answers with the actual respective freezing points: $-0\mathrm{.}348C$ and $-0\mathrm{.}470C.$ The difference is due to the decreased activity of the ions. Because of the attractive forces between the positively and negatively charged ions, they do not move completely independently of one another.$)$

$A=$

$B=$

How many grams of each of the following per kilogram of water in your car radiator are needed to give equal protection against freezing down to $-10C?($a$)$ Methyl alcohol, $C{H}_{3}OH,$ b$.$p$.64\mathrm{.}6C.($b$)$ Ethylene glycol, $C_2{H}_4(OH{)}_2,$ b$.$p$.197\mathrm{.}2C.$ In spite of higher cost, what advantage does ethylene glycol possess over methyl alcohol as a winter antifreeze and$/$or summer coolant? $($Hint figure out the number of moles of solute required to depress the freezing point of water to $-10C.$

$A=$

$B=$