Question

The vapor pressure of pure water (molar mass=18.0 g/mole) at 50°C is 92.5 mm Hg. A solution containing the nonelectrolyte sucrose (molar mass=342 g/mole) has a vapor pressure of 90.8 mm Hg at 50°c.a. what is the boiling point elevation of this solution?b. If it has density of mL what is the osmotic pressure of this solution at 50°c?​

Answer 1

To determine the molecular formula of substance Xy, we calculate the moles of solute using the mass and its molecular mass, apply Raoult's law to find the mole fraction, and use molality to find the molecular formula by calculating the number of moles of the element Y in the substance.

Step-by-step explanation:

To solve for the molecular formula of substance Xy, we first determine the number of moles of solute and solvent. We do this by using the formula for molality:

m = moles of solute / kilograms of solvent

We then apply Raoult's law to find the mole fraction of solvent and from that the moles of solute:

P(solution) = X(solvent) * P0(solvent)

where P(solution) is the vapor pressure of the solution, P0(solvent) is the vapor pressure of the pure solvent, and X(solvent) is the mole fraction of the solvent.

Then, we'll calculate the moles of solute (substance Xy) using the given mass and the molecular mass to solve for y, the number of moles of solute:

Moles of solute = mass of solute / molecular mass of solute

Finally, we'll use the values of moles of solute and solvent to find the molecular formula of Xy.