# chemistry

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I need help on these questions. They all seem pretty similar i think? i don't know what formula i am suppose to use. And what does nonvolatile mean? is that like a clue or something?

1) 2.6 g of the nonvolatile solute sucrose (C12H22O11) is added to 465 g of water at 25oC. What will be the partial pressure of the water vapor over this solution?

_____ mmhg

2) The partial pressure of water above a solution of water and a nonvolatile solute at 25oC is 19.5 mm Hg. What is the mole fraction of the solute?

3)The boiling point elevation of a solution consisting of 2.53 g of a nonvolatile solute in 96.3 g of benzene is 0.7690 C. What is the molecular weight of the unknown solute?

____g/mol

( for this one i know i am suppose to figure out the moles of it then divide the grams by the mole. HOW DO I FIND OUT THE MOLES??)

• chemistry - ,

For 1 and 2, I'll bet you can find the equations in your text under Raoult's Law. For #3, use delta T = Kb*m. You will need to look up Kb for benzene (look under boiling point elevation constant).

• chemistry - ,

a gaseous organofluorine compound has a density of 0.355 g/l at 307 degrees celsius