Pre$-$lab Assignment

Solubility and freezing point depression

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Date

Please note: Information needed to complete this assignment is given in the background section $.$

From the CRC Handbook of Chemistry and Physics ${98}^{th}$ Edition:

Solubility in mass percent for NaCl and NazCO at various temperatures:

Calculate the solubility in terms of molality at the above temperatures by canverting mass percent to

molarity. Review the definitions of mass percent and molality if needed. Assume $1\frac{g}{m}L$ density for

water.

Example calculation:

Calculate the mass of sodium chloride needed to make $50ml$ of $1$ molal solution.

Calculate the mass of sodium carbanate needed to make $2$ molal solution with $125g$ water:

Calculate the freezing point depression of $1$ molal NaCl :

Calculate the freezing point depression of $1$ molal NazCOx

The freezing paint of water was determined to be $0\mathrm{.}6C$ for the canditions in the lab that day. Determine

the thearetical freezing point of the $1$ molal NaCl and NazCO s that day:

NaCl:

$NaC{O}_3$:

Mercury $($I$)$ nitrate should have the formula $H{g}_{2}N{O}_3,$ but spectroscopic and freezing point depression

studies indicate $($and it is now accepted$)$ that in fact the formula is $H\frac{g_2}{N}{O}_3($because the mercury$($i$)$ ion

is a diatomic ion, $\{$:$H{g}^{2+}).$ What value for i would you expect for a $1m$ solution based on the formula

$HgN{O}_3?$ What would be the ivalue for $Hg$ & $?$

$HgN{O}_2=$

$Hg2(N{O}_3)2,i=$

Twa battles of alcohols $($Methanol$,$ mm $32\mathrm{.}04$g$/$mal$.$ Butanal, mm $74\mathrm{.}12$g$/$mal$)$ were stared but

unlabeled. The person who stored them has since forgatten which bottle is which. To determine which

alcohol is in each battle a $5g$ sample was taken fram bottle $11$ and mived with $100gH.$ The water used

was determined to have a freezing point of $0\mathrm{.}32C.$ The freezing point of the solution was $-2\mathrm{.}58C.$

Determine the freezing point depression of the salution: $T=32C-($:$-2\mathrm{.}58C)=2\mathrm{.}90C$

Using the freezing point depression of the solution find the molar mass of the sample taken fram bottle

#$1,$ assume $i=1.$ Equation: igrams of solute