Question

Help please!! I need to solve this,but unable.3rd one

Answer 1

Final Answer :
Vapour Pressure of solution is 17.43mmHg.

Understanding steps:
1) Raoults law tell us that in an Ideal Solution , the vapour pressure of a component is proportional to the mole of that component in solution.

2) Mole fraction of water =

No. of moles of water /( No. of moles of water + No. of moles of Sucrose)

No. of Moles of water = 1000/18= 55.55
No. of moles of sucrose = 68.4/342 = 0.2

By substituting these values, in mole fraction if water we get,

x(water) = 0.996



3) Because sucrose is involatile , the vapour pressure of the solution is proportional to the mole fraction of water.

P(solution ) = x(water) * 17.5mmHg
= 0.996*17.5mmHg
= 17.43mmHg


Hence, Vapour Pressure of solution is 17.43mmHg