Question

Butylated hydroxytoluence `(BHT)` is used as an antioxidant in processed foods ( it prevent fats and oils from becoming rancid). A solution of `2.5 g` of `BHT` in `100 g` of benzene has a freezing point of `4.88 K`. What is the molecular weight of `BHT`?
`(k_(f)("benzene")=5.12 K mol^(-1)kg`, freezing point of benzene `= 5.45 K`)

Answer 1

Given, `w_(BHT)=2.5g, W=100 g`,
`DeltaT=5.45-4.88=0.57 K, K_(f)=5.12K molality^(-1)`
`DeltaT=(1000xxK_(f)xxw)/(Wxxm)`
`0.57=(1000xx5.12xx2.5)/(100xxm)`
Mol. Weight `(m)=224.56 g//mol`