in 100g of What is the vapor is 975 mm Hg at 25 C Assume tha

in 10.0g of What is the vapor is 97.5 mm Hg at 25 \"C.) Assume that

Solution

Given:

Vapor pressure of pure cyclohexane at 25 deg C=P*=97.5 mmhg

mol of napthalene=mass /molar mass=1.0g/(128.170g/mol)=0.00780 mol

mol of cyclohexane=mass/molar mss=10.0g/84.16g/mol=0.119 mol

mol fraction of cyclohexane=mol of cyclohexane/total mol=0.119/(0.119+0.0078)=0.94

as napthalene is non-volatile ,so only cyclohexane vaporises and contributes to vapor pressure

Using raoult\'s law, Vapor pressureof solution=mol fraction*P*=0.94*97.5 mmhg=91.50mmhg

Answer:91.50 mmhg