Butylated hydroxytoluene (bht) is used as an antioxidant in processed foods. (it prevents fats and oils from becoming rancid.) a solution of 2.500 g of bht in 100.0 g of benzene had a freezing point of 4.880 oc. what is molecular mass of bht? . kf for benzene is 5.065 oc/m

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:

Knowing you have 100,0g of solvent ≡ 0,1000 kg:

= 0,01224 moles of solute ≡ BHT

As grams of BHT are 2,500, molecular mass of BHT is:

204,2 g/mol

I hope it helps