DATE:

A solution containing 1.21 g of camphor [molar mass = [tex]$152 \, \text{g/mol}$[/tex]] in 26.68 g of acetone boils at 329.95 K. The boiling point of pure acetone is 329.45 K. Calculate the molal elevation constant [tex]$K_b$[/tex] for acetone.

Given:
[tex]
\begin{array}{l}
W_1 = 26.68 \, \text{g} \, (\text{mass of acetone}) \\
W_2 = 1.21 \, \text{g} \, (\text{mass of camphor})
\end{array}
\]



Answer :

Sure! Let's go through this step-by-step:

### Given Data:
1. Weight of acetone ([tex]\( W_1 \)[/tex]) = 26.68 g
2. Weight of camphor ([tex]\( W_2 \)[/tex]) = 1.21 g
3. Molar mass of camphor = 152 g/mol
4. Boiling point of the solution = 329.95 K
5. Boiling point of pure acetone = 329.45 K

### Steps to Solve:

1. Calculate the Change in Boiling Point ([tex]\( \Delta T_b \)[/tex])
[tex]\[ \Delta T_b = \text{Boiling point of solution} - \text{Boiling point of pure acetone} \][/tex]
[tex]\[ \Delta T_b = 329.95 \, \text{K} - 329.45 \, \text{K} = 0.50 \, \text{K} \][/tex]
The change in boiling point [tex]\( \Delta T_b \)[/tex] is 0.50 K.

2. Calculate the Number of Moles of Camphor ([tex]\( n_2 \)[/tex])
[tex]\[ n_2 = \frac{\text{Weight of camphor} (W_2)}{\text{Molar Mass of camphor}} \][/tex]
[tex]\[ n_2 = \frac{1.21 \, \text{g}}{152 \, \text{g/mol}} = 0.00796053 \, \text{mol} \][/tex]
The number of moles of camphor [tex]\( n_2 \)[/tex] is approximately 0.00796053 mol.

3. Convert the Mass of Solvent (Acetone) to Kilograms ([tex]\( m_{\text{solvent}} \)[/tex])
[tex]\[ m_{\text{solvent}} = \frac{\text{Weight of acetone} (W_1)}{1000} \][/tex]
[tex]\[ m_{\text{solvent}} = \frac{26.68 \, \text{g}}{1000} = 0.02668 \, \text{kg} \][/tex]
The mass of solvent in kilograms is 0.02668 kg.

4. Calculate the Molality ([tex]\( m \)[/tex]) of the Solution
[tex]\[ m = \frac{n_2}{m_{\text{solvent}}} \][/tex]
[tex]\[ m = \frac{0.00796053 \, \text{mol}}{0.02668 \, \text{kg}} = 0.29837 \, \text{mol/kg} \][/tex]
The molality of the solution is approximately 0.29837 mol/kg.

5. Calculate the Molal Elevation Constant ([tex]\( K_b \)[/tex])
[tex]\[ K_b = \frac{\Delta T_b}{m} \][/tex]
[tex]\[ K_b = \frac{0.50 \, \text{K}}{0.29837 \, \text{mol/kg}} = 1.67577 \, \text{K} \cdot \text{kg/mol} \][/tex]
The molal elevation constant [tex]\( K_b \)[/tex] for acetone is approximately 1.67577 K·kg/mol.

Therefore, the molal elevation constant ([tex]\( K_b \)[/tex]) for acetone is 1.67577 K·kg/mol.