Steam distillation is used to purify a compound which is steam principle volatile and insoluble in water. The impurities should not be steam volatile. It is based on the principle that liquid will boil when partial vapour presure of liquid and partial vapour pressure of steam both become equal to atmospheric presure `P=p_(1)+p_(2)`.
It reduces the boiling point of liquid.
`("Wt. of water distilled")/("Wt. of substance distilled")=`
`("M. Wt. of water" xx V.P. " of steam")/(M. Wt. "of substance" xx "V.P. substance")`
Whilch of the following is steam volatile?
A. o- nitrophenol
B. p-nitophenol
C. p-hydroxybenzaldehyde
D. Ethanol
