A 2.500×10−2M solution of NaCl in water is at 20.0∘C. The sample was created by dissolving a sample of NaCl in water and then bringing the volume up to 1.000 L. It was determined that the volume of water needed to do this was 999.3mL . The density of water at 20.0∘C is 0.9982 g/mL.

Question

A 2.500×10−2M solution of NaCl in water is at 20.0∘C. The sample was created by dissolving a sample of NaCl in water and then bringing the volume up to 1.000 L. It was determined that the volume of water needed to do this was 999.3mL . The density of water at 20.0∘C is 0.9982 g/mL.
A) Calculate the molality of the salt solution.
B) Calculate the mole fraction of salt in this solution.
C) Calculate the concentration of the salt solution in percent by mass.
D) Calculate the concentration of the salt solution in parts per million.

DrBob222 · Answer

You must know how to do parts of this. What about the problem do you not understand?
a. m = mols/kg solvent. You have volume and density. That's how you determine kg solvent.

b. XNaCl = n/total mols
XH2O - n/total mols

c. % NaCl w/w = grams NaCl/100 g solution.

d. Take the answer from c (which is parts per hundred) and multiply by 10,000.