Question

214.2 gram of sugar syrup contains 34.2 gram of sugar. Caluculate (i) molality of the solution and (ii) mole fraction of the sugar in the syrup-
A. 0.555m, 0.0099
B. 0.4565m,0.0110
C. 0.355m, 0.0199
D. None of these

Answer 1

Correct Answer - A
Mass of sugar=34.2 gram. Number of moles of sugar`=34.2/("mol. mass")=34.2/34.2=0.1`
Mass of water `=(214.2-34.2)=180" gram or "180/1000kg`
Number of moles of water `=180/18=10`
`"Molality"=("No. of moles of sugar")/("Mass of water in kg")=0.1/180xx1000=0.555m`
(ii) Total no. of moles`=10.0+0.1=10.1`
Mole fraction of sugar `=("No. of moles of sugar")/("Total number of moles")= 0.1/10.1=0.0099`