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When 6.27 g of a certain molecular compound x are dissolved in 40.0 g of formamide (nh2coh) the freezing point of the solution is measured to be 1.6 °c.rncalculate the molar mass of X.rnFormamide (molal freezing point depression constant: 4.25). Also, be sure your answer has a unit symbol, and is rounded to the correct number of significant digits.
Accepted Answer
Molality of the solution, m = (moles of solute / kg of solvent)
Change in freezing point, ΔTf = Kf * m = 1.6 °C
Kf for formamide is 4.25 °C/molality
6.27 g of the solute X is dissolved in 40.0 g of formamide
Converting the mass of the solute and solvent into the number of moles:
moles of solute X = 6.27 g / molar mass
moles of solvent = 40.0 g / 45.01 g/mol = 0.889 mol
Substituting the values of ΔTf, Kf, and moles of solvent into the equation:
1.6 °C = 4.25 °C/molality * (moles of solute / 0.889 mol)
Solving for the moles of solute, we get:
moles of solute = 0.0566 mol
Now that we have the number of moles of the solute, we can calculate the molar mass (M) of X:
M = mass of the solute (g) / moles of the solute (mol)
M = 6.27 g / 0.0566 mol
The molar mass of the molecular compound X is approximately 110.8 g/mol.
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