# ap chem

posted by
**just** on
.

a solution is prepared by dissolving 4.87 g of sodium dichromate in 25.0 ml of water. (d=1.00g/mL).calculate

a. the mass percent of sodium dichromate in the solution.

b. the mass percent o water in the solution.

c the mole fraction of sodium dichromate in the solution.

How much of this do you know how to do?

Show as much as you can do and I can help from there.

well mass percent is mass solute divided by total mass solution times 100..so would it be..25.0/4.87 x 100?

Your formula is ok. Your use of it is not.

[mass solute/total mass]x100=

4.87 g Na2Cr2O7 is the solute.

Total mass = 4.87 + 25 = ??

You do the math.

b) Solvent is water so mass percent H2O = mass H2O (25 g)/total mass

total mass still 4.87 + 25 = ??

You do the math.

c) mol fraction Na2Cr2O7 =

mols Na2Cr2O7/total mols.

mol Na2Cr2O7 = 4.87/molar mass = ??

mol H2O = 25 g/molar mass H2O = ??

You do the math.

Post your work if you get stuck.