Respuesta :
Answer:
Molar mass of vitamin K = 450.56\frac{g}{mol}[/tex]
Explanation:
The freezing point of camphor = 178.4 ⁰C
the Kf of camphor = 37.7°C/m
where : m = molality
the relation between freezing point depression and molality is
Depression in freezing point = Kf X molality
Where
Kf = cryoscopic constant of camphor
molality = moles of solute dissolved per kg of solvent.
putting values
2.69°C = 37.7°C/m X molality
molality = 0.0714 mol /kg
[tex]molality=\frac{molesofvitaminK}{massofcamphor(kg)}=\frac{moles}{0.025}[/tex]
moles of vitamin K = 0.0714X0.025 = 0.00178 mol
we know that moles are related to mass and molar mass of a substance as:
[tex]moles=\frac{mass}{molarmass}[/tex]
For vitamin K the mass is given = 0.802 grams
therefore molar mass = [tex]\frac{mass}{moles}=\frac{0.802}{0.00178}=450.56\frac{g}{mol}[/tex]
