Question

What is the molarity of an aqueous solution that is 6.03 % nacl by mass? (assume a density of 1.02 g/ml for the solution.) (hint: 6.03 % nacl by mass means 6.03 g nacl/100.0 g solution.)?

Answer 1

1) Molarity = mol solute/Volume solution (L)
2) Lets take 6.03 g NaCl in 100.0 g solution
3) Molar mass (NaCl)= 23.0+35.5=58.5 g/mol
6.03 g NaCl*(1mol NaCl/58.5 gNaCl)=0.103 mol NaCl
4) 100.0 g soltion*(1ml/1.02g)=98.0 ml
98.0 ml = 0.0980 L volume of solution
5)Molarity = mol solute/Volume solution (L)
Molarity = 0.103 mol NaCl/0.0980 L volume of solution=1.05 mol/L
Molarity of this solution is 1.05 M