Practicing Success
At what temperature a solution containing \(5.60 g\) of glucose per \(1000 g\) of water would boil at \(1.013\, \ bar\)? (k for water is \(0.52\, \ K\, \ kg\, \ mol^{-1}\)). |
203.321 K 273.15 Κ 303.202 Κ 373.166 K |
373.166 K |
The correct answer is option 4. 373.166 K. To calculate the boiling point elevation, we can use the formula: \[ \Delta T_b = i \times K_b \times m \] Where: \( \Delta T_b \) is the boiling point elevation, \( i \) is the van't Hoff factor, \( K_b \) is the ebullioscopic constant (molal boiling point elevation constant), \( m \) is the molality of the solute. Given that the solution contains \(5.60 \, g\) of glucose per \(1000 \, g\) of water, we need to find the molality (\( m \)) of the solution. The molar mass of glucose (\( C_6H_{12}O_6 \)) is \( 180.16 \, g/mol \). \[ \text{Moles of glucose} = \frac{5.60 \, g}{180.16 \, g/mol} \approx 0.0311 \, mol \] Since the mass of water is \(1000 \, g\), the mass of the solvent (water) is \(1000 - 5.60 = 994.40 \, g\). \[ \text{Molality} \ (m) = \frac{\text{moles of solute}}{\text{mass of solvent (kg)}} = \frac{0.0311 \, mol}{0.9944 \, kg} \approx 0.0313 \, mol/kg \] Now, we can calculate the boiling point elevation (\( \Delta T_b \)): \[ \Delta T_b = i \times K_b \times m \] Given that water is the solvent, \( i = 1 \). Given \( K_b = 0.52 \, K \, kg \, mol^{-1} \). \[ \Delta T_b = 1 \times 0.52 \, K \, kg \, mol^{-1} \times 0.0313 \, mol/kg \] Finally, we can calculate the boiling point of the solution: \[ T_{b \text{, solution}} = T_{b \text{, pure solvent}} + \Delta T_b \] The boiling point of pure water at \(1.013 \, \text{bar}\) is \(373.15 \, K\). \[ T_{b \text{, solution}} = 373.15 \, K + 0.0164 \, K \] \[ T_{b \text{, solution}} \approx 373.166 \, K \] So, the boiling point of the solution is approximately \(373.166 \, K\). Therefore, the correct answer is option 4. |