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When 1.2 g of Sulphur is melted with 15 ...

When 1.2 g of Sulphur is melted with 15 g of naphthalene, the solution freezes at`77.2^(@)C`. What is the molar mass of this form of Sulphur?
Deta for napthalene:
Melting point (f.pt.) ` 80.0^(@)C`
Freezing point depression constant `K_(f) 6.80Km^(-1)`

A

`180g "mol"^(-1)`

B

`190g "mol"^(-1)`

C

`260g "mol"^(-1)`

D

`450g "mol"^(-1)`

Text Solution

Verified by Experts

`DeltaT=K_(f)xx(W(B)xx1000)/(m_(B)xxw_(A))impliesm_(B)=(K_(f))/(Deltat)xx(W_(B)xx1000)/(w_(A))=6.8/2.8xx(1.2xx1000)/15=190`
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