Question

Calculate the ionic strength of 0.2 M solution of Calcium chloride?

(a) 0.9 M

(b) 0.06 M

(c) 0.6 M

(d) 6.0 M

This question was addressed to me in an online quiz.

The origin of the question is Enzyme Kinetics Fundamentals topic in chapter Enzyme Kinetics Fundamentals of Enzyme Technology

Answer 1

Right option is (c) 0.6 M

The explanation is: Ionic strength is given by the equation I = 0.5∑ci zi^2

Where ci = concentration of every ionic species, zi = Charge of every ionic species.

Charge of chlorine and calcium is -1 and +2 respectively.

Concentration of calcium = 0.2 * 1 = 0.2

Concentration of chlorine = 0.2 * 2 = 4

I = 0.5 (0.2[2]^2 + 0.4 [-1]^2)

I = 0.5(0.8 + 0.4)

I = 0.6 M.