Question

what is the molarity of a solution of potassium dichromate (k2cr2o7) if 187 grams are dissolved in 250 ml?

Answer 1

Answer:
            Molarity  =  2.54 mol.L⁻¹

Solution:
              Molarity is the amount of solute dissolved per unit volume of solution. It is expressed as,

                          Molarity  =  Moles / Volume of Solution    ----- (1)

Data Given;
                   Mass  =  187 g

                   Volume  =  250 mL  =  0.25 L

First calculate Moles for given mass as,

                    Moles  =  Mass / M.mass

                    Moles  =  187 g / 294.185 g.mol⁻¹

                    Moles  =  0.6356 mol

Now, putting value of Moles and Volume in eq. 1,

                         Molarity  =  0.6356 mol ÷ 0.25 L

                         Molarity  =  2.54 mol.L⁻¹