# chemistry

posted by .

a student needs to prepare an aqueous solution of sucrose at a temperature of 20 degrees c with a vapor pressure of 15. 0 mm Hg. How many grams of sucrose (mm=342 g/mol) does she need if she uses 375 g H20? (the vapor pressure of water at 20 degrees c is 17.5 mm Hg)

• chemistry -

Psoln = XH2O*PoH2O
15.0 torr = XH2O*17.5 torr
Solve for XH2O which gives you the mole fraction that H2O must be. I'll call that ??

[molesH2O/(moles H2O + moles sucrose)]=??

moles H2O = grams water/molar mass H2O, substitute this into the equation immediately above this (both numerator and denominator) and solve for moles sucrose.

Finally, moles sucrose = grams/molar mass sucrose.

Then check everything to make sure all of that gives you 15.0 torr.

## Similar Questions

1. ### chemistry

The molar mass of sucrose, or table sugar, is 342 grams. Calculate how many grams of sucrose are required to make 3.0 liters of 0.50M sucrose solution.
2. ### Chemistry

The boiling point elevationof an aqueous sucrose solution is found to be 0.39 degrees Celsius. What mass of sucrose (molar mass=342.30g/mol) is contained in 500g of the solution?
3. ### chemistry

a sucrose solution with a volume of B uL has a density of C g/ml. the solution is D % sucrose by mass. if i added x ml of this sucrose to another solution, how many grams sucrose did I add?
4. ### CHM

How many milliliters of a 0.25 M sucrose solution contain 2.0 grams?
5. ### CHM formula needed, pls?

How many milliliters of a 0.25 M sucrose solution contain 2.0 grams?
6. ### Chemistry

What is the osmotic pressure in atmospheres of a 50% sucrose solution at a temperature of 37 degrees celcius with molar mass of 342.30grams of sucrose
7. ### Chemistry

What is the osmotic pressure of a 50% sucrose solution at a temperature of 37 degrees celcius with a molar mass of sucrose of 342.30 grams
8. ### Biology

A student wishes to prepare 300 mL of 0.25 M sucrose. He puts 25.7 g of sucrose in a beaker and then adds 300 mL of dH2O. The total volume of the solution after the sucrose has been dissolved is 330 mL. a) What did he do wrong when …
9. ### Chemistry

You purchased a 5.00 pound bag of sugar (sucrose, C12H22O11) at the grocery last week to bake cookies. Conversion: 1 pound = 1 lb = 454 grams. a.How many grams of sucrose did you purchase?
10. ### Chemistry

How many grams of sucrose will be necessary to prepare 300 ml of a 5% solution of sucrose (342.0 g/mol)

More Similar Questions