Question

How do you would prepare a 2.00 M solution of sodium chloride?

Answer 1

We know molarity is the number of moles of solute dissolved in one litre of the solution .

                  M = number of moles / volume of solution in L

Given molarity of sodium chloride solution is = 2.00 M

                                                                      = 2.00 mol / L

That means 1L of the solution contains 2.00 mol of NaCl ( sodium chloride)

If we want to prepare 1L of the solution , then the number of moles of solute dissoved is 2.00 mol

We know that number of moles , n = mass/molar mass

Molar mass of NaCl = At.mass of Na + At.mass of Cl

                               = 23 + 35.5

                               = 58.5 g / mol

So mass of NaCl , m = Number of moles x molar mass

                                = 2.00 mol x 58.5 (g/mol)

                                = 117 g

Therefore the mass of NaCl present in NaCl solution is 117 g .

So exactly weigh & transfer 117 g of NaCl salt in a 1000 mL(=1L) volumetric flask and add little amount of distilled water and dissolve the contents.After complete dissolution add distilled water upto the mark on the neck of the volumetric flask.This is the required solution.