Solutions and Molarity

The substance that is more plentiful in a solution

The substance that is less plentiful in a solution

A homogeneous mixture of two or more substances

Molarity is the most common method to represent the concentration of solute particles in solution. $\text{Molarity} = \frac{\text{mol solute}}{\text{L solution}}$

A 3.75g sample of NaCl is dissolved in water. The total volume of the solution is 768mL. What is the molarity of the solution?

$3.75\text{g NaCl} \times \frac{1 \text{ mol NaCl}}{58.44 \text{ g NaCl}} = 0.0642 \text{ mol NaCl}$

$\text{Molarity} = \frac{0.0642 \text{ mol}}{0.768 \text{ L}} = 8.36\times10^{-2} \text{ M NaCl}$

When ionic compounds dissolve in water, it dissociates. These are known as electrolytes.

Common electrolytes include:

• NaCl (salt)
• NaNO₃ (sodium nitrate)
• CaCl₂ (calcium chloride)

Lowering the concentration of solution (by adding more solvent)