CBSE Class 11-science Answered

Mass of pure compound (NaOH),m= S.G X V X % composition

Where SG is specific gravity

      V is volume of solution; assume it to be 1 L or 1000 ml

      % composition means xg of pure compound per 100g of solution

Since NaOH is 50% by weight so, it means

28.3 % by wt NaOH maens 50 gm NaOH + 50 gm H₂O = 100 gms

So, mass of NaOH in solution will be= 1.52 X 1000 X 0.50 = 760 gms NaOH/L

Now, molar mass of NaOH = 40 gm/mol

So, molar concentration of NaOH= Mass of NaOH in solution/ Molar mass

                                                        = 760 gms/40 gm/mol
                                                        = 19 mol/L = 19 M

molar concentration of NaOH = 19 M