Question

1. How much NaCl would you need to weigh out to prepare 100 mL of a 2.5% NaCl solution?

Answer 1

Answer - 5.85g

Solution -

Using the concentration equation, m = CVMo where m is the mass of solute, C is the concentration (M), V is the volume of solution (L) and Mo is molar mass of the solute (g):

Given,

Molar mass of NaCl, M = 58.5g/mol

Volume of the solution, V= 100ml = 0.1L

Molarity, S= 1M

Mass of the solute,W=?

W=SMV

= 1×58.5×0.1

= 5.85g