CHEM HELP PLEASE? Solution problem involving mass percent? What is the mass % of ammonium chloride in the solution?

Question

At 20°C, a 3.54 M aqueous solution of ammonium chloride has a density of 1.0512 g/mL. The formula weight of NH4Cl is 53.50 g/mol.

options:
6.95
3.36
0.297
4.10
18.00

I know mass % = mass of solute/mass of solution, but these mass values are not given directly and I don't know how to solve for them. Thank you for the help!

Answer 1

1) Find Weight of 3.54 moles of NH4Cl in 100 mL of solution.

 

Mass=Moles*Molar Mass or 53.50*3.54 or 189.39 grams.

 

grams NH4Cl per mL= 189.39 g/1000 mL or 0.18939 g/mL

 

mass% NH4Cl=(mass of NH4Cl/Mass of solution)*100%

 

mass% NH4Cl=(0.18939/1.0512)*100% or 18.02% or 18%