Step 1
The equation for the boiling point elevation used here:
m = molality, which is calculated as follows:
Kb = boiling constant
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Step 2
Information provided:
Solute = C9H8O
Solvent = carbon tetrachloride
Mass of solute = 97.1 mg
(1 g = 1000 mg => 97.1 mg x (1 g/1000 mg) = 0.0971 g)
Mass of solvent = 1.00 g
(1 kg = 1000 g => 1.00 g x (1 kg/1000 g) = 1x10^-3 kg)
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Information needed:
The molar mass of solute = 132.1 g/mol (please, the periodic table is useful here)
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Step 3
The number of moles of solute: n
n = mass of solute/the molar mass of solute = 0.0971 g/ 132.1 g/mol = 7.35x10^-4 moles
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Molality, m:
m = moles of solute/mass of solvent (kg) = 7.35x10^-4 moles/1x10^-3 kg = 0.735 moles/kg or m
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The boiling point elevation:
ΔTb = Kb x m = 5.03 °C/m x 0.735 m = 3.69 °C
Answer: ΔTb = 3.69 °C