PCH 211: Solutions - General and Inorganic Pharmaceutical Chemistry

A set of vocabulary flashcards defining fundamental solution concepts, concentration expressions (molarity, molality, normality), equivalent weight, and colligative properties from PCH 211.

Solution

A homogeneous mixture of two or more substances, consisting of a solute dissolved in a solvent (for example, salt dissolved in water to make salt water, or $CO_2$ dissolved in water to make carbonated drinks).

Solute

The substance dissolved in a solvent to form a solution, representing the dissolved component or unknown substance being measured.

Solvent

The dissolving medium in a solution (such as water) that dissolves the solute and determines the physical state of the solution.

Molarity ($M$)

The concentration of a solution expressed as the number of moles of solute per litre of solution ($M = \frac{\text{no. of moles}}{\text{litre of solution}}$), also referred to as molar concentration.

Mole

A standard scientific unit of measurement used to quantify the amount of any chemical substance.

Mass Concentration

The concentration of a solute expressed in $g/dm^3$, calculated by multiplying the moles per $dm^3$ by the molar mass ($\text{Mass concentration} = \text{Moles per } dm^3 \times \text{molar mass}$).

Molar Concentration

The concentration of a solute expressed in $mol/dm^3$, calculated by dividing the mass concentration in grams per $dm^3$ by the molar mass ($\text{Molar concentration} = \frac{\text{Grams per } dm^3}{\text{molar mass}}$).

Molality ($m$)

The concentration of a solute in a solution defined as the number of moles of solute per kilogram of solvent ($m = \frac{\text{no. of moles of solute}}{\text{kilogram of solvent}}$), also known as molal concentration.

Molal Solution

A solution that has a concentration of $1\,mol/kg$ of solvent, denoted as $1\text{ molal}$.

Colligative Properties

Physical properties of a solution that depend on the concentration of solute particles rather than the identity of the solute; primary examples include boiling point elevation, vapour pressure lowering, freezing point depression, and osmotic pressure.

Normality ($N$)

A concentration unit defined as the number of gram equivalent weights of solute per litre of solution ($N = \frac{\text{equiv. wgt}}{L}$), or calculated as the product of molarity and the equivalent number ($N = M \times n$).

Equivalent Number ($n$)

The number of reactive units transferred per molecule or formula unit, including the number of electrons or protons transferred in a redox reaction, the valence state of an ion, or the number of replaceable hydrogen ions ($H^+$) or hydroxide ions ($OH^-$) in acid-base reactions.

Normal Solution

A solution containing $1\text{ gram equivalent weight}$ of dissolved solute per $1\text{ litre}$ ($1000\,ml$) of solution, such as a $1N$ or $0.1N$ solution.

Equivalent Weight (Equivalent Mass)

The mass in grams of a substance that reacts with or replaces a standard reference element or compound, calculated as the molar mass divided by the equivalent number ($\text{Equivalent weight} = \frac{\text{molar mass}}{n}$).

Density ($d$)

The mass of a substance divided by its volume ($d = \frac{m}{v}$), typically expressed in units of $g/ml$ or $g/cm^3$, used to convert between volume-based (molarity) and mass-based (molality) concentration units.