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Ionic Strength Calculator

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When an ionic compounds are dissolved in water, they dissociate into ions. The concentration of ions present in the solution is measured by the ionic strength of the solution. If the concentration of ions increases, then the ionic strength also increases.

The ionic strength of the solution is calculated by the formula,

I = $\frac{1}{2}\sum_{i=1}^{n}c_{i}z_{i}^{2}$

Where,
I = ionic strength of the solution,
c = concentration of the ion,
z = charge of the ion.

The ionic strength calculator helps determine the ionic strength of the solution when you plug in the concentration and the oxidation of the element into the ionic strength calculator.

Steps

Step 1 : Make a note of the concentration of the solution from the question.

Step 2 : Find the charge of each element of the whole compound and subsitute the values into the ionic strength formula to get the ionic strength of the solution.
I = $\frac{1}{2}\sum_{i=1}^{n}c_{i}z_{i}^{2}$.

Problems

There are some solved problems based on ionic strength to make you understand properly.

Solved Examples

Question 1: Determine the ionic strength of the solution whose concentration are 1.0 M $La_{2}(SO_{4})_{3}$ and 1.0 M $CaCl_{2}$.
Solution:

Concentration for the given solution are,
[$La^{3+}$] = 2.0 M
[$SO_{4}^{2-}$] = 3.0 M
[$Ca^{2+}$] = 1.0 M
[$Cl^{-}$] = 2.0 M

I = $\frac{1}{2}\sum_{i=1}^{n}c_{i}z_{i}^{2}$

I = $\frac{1}{2}$$(2 \times (3)^{2} + 3 \times (2)^{2} + 1 \times (2)^{2} + 2 \times (1)^{2}) I = 18.0 Question 2: Determine the ionic strength of 0.10 M NaNO_{3}. Solution: Concentration for the given solution are, [Na^{+}] = 0.10 [NO_{3}^{-}] = 0.10 I = \frac{1}{2}\sum_{i=1}^{n}c_{i}z_{i}^{2} I = \frac{1}{2}$$(0.10 \times (1)^{2} + 0.10 \times (1)^{2})$

I = 0.10 M