Relation between Molarity and %by weight and density.

Formula of Molality= Numbers of moles of solute/volume of solution in litre

If ,

                  % m/m=  x%

                   density=  d

Let consider mass of solution be 100 g

Then mass of solute = x gm

Also, density of solution  = mass of solution/Volume of solution

Volume of solution = mass of solution/ density of solution

If volume is in ml, then to convert it in litre

Volume of solution in litre= mass of solution/density of solution× 1000

Moles = weight/ molecular mass(M°)

Keeping all these in formula of molarity

Molarity= %w ×d×1000/M°×100

=%w×d×10/M°

So, molarity=    %w×d×10

                           ⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻

                                 M°

  What is the molarity of pure water?

Let us take 100 g water , Density of water is 1 gm/ml 

%w/w                          = 100%

Density (d)                 = 1 gm/ml

Molecular mass(M°)= 18g

Molarity=         %w×d×10

                           ⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻

                                 M°

Molarity=          100×1×10

                           ⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻ = 55.5 M

                                18

**************************************************