Question

Find the inonic force of the following solutions

a) 0.030M FeSO₄

b) 0.30M (NH₄)₂CrO₄-

c) 0.030M La(NO₃)₃ + 0.060M Fe(NO₃)₂

Note: if you attempt this question please solve all parts (a, b and c) or else your answer will be rated as wrong/reported.

Answer 1

Ionic force = 1/2 X { strength of solution in M X # of ions X( charge of the ion)² for all the ions present in solution

For 0.03 M FeSO4,

1/2 X {(0.03M X # of Fe ions X (charge of Fe ions)² + 0.03M X # of SO4 ions X( charge of SO4 ions)²

1/2{(0.03M X 1 X 2²+0.03M X 1 X (-2)²)}

1/2(0.24)

=0.12 M

Similarly for 0.03M( NH4)2 CrO4-  

1/2X { (0.03M X 2 X 1² + 0.03M X 1 X (-2)²)}

=0.09M

For 0.03 M La(NO3)3   + 0.06 M Fe(NO3)2

1/2 X {(0.03 M X 1 X 3² + 0.03 M X3 X (-1)² ) + ( 0.06 M X 1 X 2² + 0.06 M X 2 X (-1)²)}

=0.36 M