IB Chemistry S1.4.5 Molar Concentration Notes

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Molar Concentration: Definition, Units, and Applications

What you’re doing is intuitively changing the concentration of sugar in the solution.

Molar Concentration: The Core Definition

Mathematically, it is expressed as:

$$
C = \frac{n}{V}
$$ where:

1. $C$ = molar concentration (in $\text{mol dm}^{-3}$)
2. $n$ = amount of solute (in moles)
3. $V$ = volume of the solution (in dm³)

Writing Concentration: The Square Bracket Notation

1. In IB Chemistry, square brackets around a chemical formula denote its molar concentration in $\text{mol dm}^{-3}$.
2. For example, $[\text{NaCl}] = 1.0 \ \text{mol dm}^{-3}$ means a solution containing 1.0 mol of sodium chloride per cubic decimetre.

Why Use Molar Concentration?

1. Molar concentration bridges the macroscopic (measurable quantities like volume) with the microscopic (the number of particles in a solution).
2. For instance, knowing the concentration of a reactant helps calculate how much product a reaction will yield.