Question

An NaCl solution is made using 133g of NaCl ane diluting it to a total volume of 1.00L .Calculate the molarity (M) and mass percent of the solution (%(m/m)).Assume a solution density of 1.08 g/mL.
M=?
(%(m/m))=?
I got a M=2.27 M and %(m/m)=12.31%

Answer 1

1)

Molar mass of NaCl,

MM = 1*MM(Na) + 1*MM(Cl)

= 1*22.99 + 1*35.45

= 58.44 g/mol

mass(NaCl)= 133 g

use:

number of mol of NaCl,

n = mass of NaCl/molar mass of NaCl

=(1.33*10^2 g)/(58.44 g/mol)

= 2.276 mol

volume , V = 1 L

use:

Molarity,

M = number of mol / volume in L

= 2.276/1

= 2.276 M

Answer: 2.28 M

2)

volume of solution = 1 L = 1000 mL

mass of solution = volume * density

= 1000 mL * 1.08 g/mL

= 1080 g

mass % = mass of NaCl * 100 / mass of solution

= 133 * 100 / 1080

= 12.31 %

Answer: 12.3 %