Calculate the vapour pressure of a solution at `100^@C` containing `3`g of cane sugar in `33`g of water.(Atwt.C =`12`,h=`1`,O=`16`)

Options

A. 760 mm
B. 756.90 mm
C. 758.30 mm
D. None

Answer

B

Explanation

Vapour pressure of pure water (solvent) at `100^@C,P^@` = 760 mm
Vapour pressure of solution, p = ?
Wt. of solvent , W = 33g
Wt. of solute , w = 3g
Mol. wt. of water `(H_2O)`, M = 18
Mol. wt. of sugar `(C_12H_22O_11)`,
m = `12 xx 12 + 22 xx 1 + 11 xx 16 = 342`
According to Raoult’s law ,
`(p^@-p)/p^@=(wM)/(Wm)`
`p=p^@-(wxxM)/(mxxW)xxp^@`
`p=760-(3xx18)/(342xx13)xx760`
`(::.p^@" for "H_2O=760mm)`
= 760 – 3.19 = 756.90 mm