Question

2.82 g of glucose (molar mass = 180 g mol\(^{-1}\)) is dissolved in 30 g of water. Calculate the molality of the solution.

Hint:

Molality is independent of temperature because it is based on mass, unlike molarity which depends on volume.

Answer 1

Step 1: Formula for Molality: \[ \text{Molality} (m) = \frac{\text{Moles of solute}}{\text{Mass of solvent (kg)}} \] Step 2: Calculate Moles of Glucose: \[ \text{Moles} = \frac{2.82}{180} = 0.01567 \text{ mol} \] Step 3: Convert Solvent Mass to kg: \[ 30 \text{ g} = 0.030 \text{ kg} \] Step 4: Calculate Molality: \[ m = \frac{0.01567}{0.030} = 0.522 \text{ mol/kg} \] Thus, the molality of the solution is 0.522 mol/kg.