Question

The vapor pressure of water at 45oC is 71.88 mmHg. What is the vapor pressure of a sugar (C12H22O11) solution made by dissolving 50.36 g of sugar in 88.69 g of water

Answer 1

Answer:

69.79 mmHg is the pressure for the solution

Explanation:

Formula for vapor pressure lowering:

Vapor pressure of pure solvent(P°) - Vapor pressure of solution (P') = P° . Xm

Xm → Molar fraction of solute (moles of solute / Total moles)

Total moles = Moles of solute + Moles of solvent

Let's determine the moles:

50.36 g . 1mol/342 g = 0.147 moles of sugar

88.69 g. 1mol/ 18g = 4.93 moles of water

Total moles = 0.147 + 4.93 = 5.077 moles

Xm = 0.147 / 5.077 = 0.0289

If we replace data given in the formula:

71.88 mHg - P' = 71.88 mmHg . 0.0289 . 0.0289

P' = - (71.88 mmHg . 0.0289 - 71.88 mmHg)

P' = 69.79 mmHg