Answer:
Molecular mass of BHT is 204,2 g/mol
Explanation:
To answer this question you need to know that Freezing-point depression (A colligative property) is the decrease of the freezing point of a solvent on the addition of a non-volatile solute. The formula is:
ΔT = Kf m
Where ΔT is the freezing point depression (5,5°C - 4,880°C = 0,62°C
Kf that is freezing point molar constant of the solvent (5,065°C/m)
And m that is molality (moles of solute/kg of solvent). Replacing:
[tex]m = 0,1224 \frac{mole Solute}{kgSolvent}[/tex]
Knowing you have 100,0g of solvent ≡ 0,1000 kg:
[tex]\frac{0,1224 moles}{1 kg Solvent} *0,1000 kg[/tex] = 0,01224 moles of solute ≡ BHT
As grams of BHT are 2,500, molecular mass of BHT is:
[tex]\frac{2,500g}{0,01224 moles BHT} =[/tex] 204,2 g/mol
I hope it helps
