Question

1) If exactly 100.0 grams of NaCl (mm=58.44g/mol) are dissolved in 300 grams of water (mm=18.02g/mol), the mole fraction of NaCl is?

a) 1.71
b) 0.0932
c) 0.250
d) 0.103
e) 4.75

I did 100g / 100g + 300g = 100/40 = 0.250.

Did I do this correctly?

Answer 1

No. mole fraction NaCl = moles NaCl/total moles.
moles NaCl = grams/molar mass NaCl
moles H2O = 300/molar mass H2O

Answer 2

Ok so 100/58.44= 1.71

Answer 3

yes. 1.71 mol NaCl
300/18.02 = 16.65
XNaCl = 1.71/(1.71+16.65) = ?

Answer 4

Ok now I got 0.0931, so this is the mole fraction for NaCl?

Answer 5

yes.