Question

The molecular mass of MgCl2 is 95.2 g/mole. If 190.4 g of MgCl2 is dissolved in 1kg of pure water, what is the normality (in eq/kg of Mg2+ and Cl-) of the solution?

Answer 1

Solution--

Equivalent weight of salt--

=molar mass of salt/total number of positive or negative charge

Molar mass of MgCl2 =95.2gram/ mole

MgCl2---> Mg^2+ + 2Cl^(-1)

Hence, equivalent weight =95.2/2

=47.6

Hence, number of equivalent = grams of solute/ equivalent weight

=190.4gram/47.6

=4 equivalent

Normality of MgCl2 in equivalent/ kg

=4equivalent /1kg

=4eq/kg

Normality of Mg^2+ =Normality of MgCl2 = 4eq/Kg

Normality of Cl^(-1) =2× normality of MgCl2= 4×2 =8 eq/Kg