what is the boiling point elevation when 31.5 g of menthol (C10H20 O ) is dissolved in 258g of acetic acid? Kb for acetic acid is 3.07 C/m.
mols MeOH = grams/molar mass
molality = moles MeOH/kg solvent
delta T = Kb*m
Solve for delta T.
To calculate the boiling point elevation when a solute is dissolved in a solvent, you can use the formula:
ΔTb = Kb * m * i
Where:
ΔTb = boiling point elevation
Kb = molal boiling point elevation constant (specific to the solvent)
m = molality of the solute (moles of solute per kg of solvent)
i = van't Hoff factor (the number of particles into which the solute dissociates in the solvent)
To calculate the molality of the solute, you need to know the number of moles of the solute and the mass of the solvent:
Step 1: Calculate the number of moles of menthol (C10H20O):
Given mass of menthol = 31.5 g
Molar mass of menthol (C10H20O) = (10*12.01) + (20*1.01) + 16.00 = 156.27 g/mol
Number of moles of menthol = mass of menthol / molar mass of menthol
Number of moles of menthol = 31.5 g / 156.27 g/mol
Step 2: Calculate the molality (m) of the solute (menthol):
Given mass of acetic acid (solvent) = 258 g (convert to kg: 258 g / 1000 = 0.258 kg)
Molality (m) = Total moles of solute / Mass of solvent in kg
Molality (m) = (moles of menthol) / (mass of acetic acid in kg)
Step 3: Calculate the boiling point elevation (ΔTb):
Given Kb (boiling point elevation constant for acetic acid) = 3.07 °C/m
Van't Hoff factor (i) for menthol is generally assumed to be 1 for non-electrolytes.
ΔTb = Kb * m * i
Finally, substitute the values into the formula to find the boiling point elevation (ΔTb).
Note: Make sure to use the appropriate unit conversions while performing calculations to ensure consistent units throughout the equations.