Class XII Chemistry - Physical Chemistry: Solutions

Comprehensive vocabulary flashcards covering concentration units, solubility, Henry's law, Raoult's law, ideal and non-ideal behaviors, colligative properties, osmosis, and abnormal molar masses based on Class XII Chemistry Unit 1 (Solutions).

Solution

A homogeneous mixture of two or more components whose composition and properties are uniform throughout the mixture.

Solvent

The component of a solution present in the largest quantity, which determines the physical state of the resulting solution.

Solute

One or more components present in a solution other than the solvent.

Binary Solution

A solution consisting of exactly two components: one solute and one solvent.

Mass Percentage ($w/w\,\%$)

A concentration unit defined as the mass of a component per $100\,\text{g}$ of the solution, which is independent of temperature.

Volume Percentage ($V/V\,\%$)

A concentration unit defined as the volume of a liquid component dissolved per $100\,\text{mL}$ of total solution; depends on temperature.

Mass by Volume Percentage ($w/V\,\%$)

A concentration unit representing the mass of solute in grams present in $100\,\text{mL}$ of solution, commonly used in medicine and pharmacy.

Parts Per Million ($\text{ppm}$)

A concentration unit defined as the parts of a component per $10^6$ parts of the solution, used when a solute is present in trace quantities.

Mole Fraction ($x$)

A dimensionless concentration term defined as the ratio of the number of moles of a particular component to the total number of moles of all components present in the solution.

Molarity ($M$)

The number of moles of solute dissolved per litre ($\text{mol}\,\text{L}^{-1}$ or $\text{mol}\,\text{dm}^{-3}$) of solution; it changes with temperature due to liquid volume expansion.

Molality ($m$)

The number of moles of solute present per kilogram ($\text{mol}\,\text{kg}^{-1}$) of solvent; it is independent of temperature because mass does not vary with temperature.

Solubility

The maximum amount of a substance that can be dissolved in a specified amount of solvent at a specified temperature and pressure.

Saturated Solution

A solution in which no more solute can be dissolved at the same temperature and pressure, existing in dynamic equilibrium with undissolved solute.

Unsaturated Solution

A solution containing less solute than its saturation limit, in which more solute can still be dissolved at the specified temperature.

Henry's Law

A law stating that at constant temperature, the partial pressure ($p$) of a gas in the vapour phase is directly proportional to the mole fraction ($x$) of the gas in the solution: $p = K_H x$.

Henry's Law Constant ($K_H$)

The proportionality constant in Henry's law ($p = K_H x$), which is a function of the nature of the gas, the solvent, and temperature; a higher $K_H$ indicates lower gas solubility.

The Bends

A painful and hazardous medical condition in scuba divers caused by rapid ascent to the surface, which causes dissolved nitrogen gas to form bubbles in the blood that block capillaries.

Anoxia

A physiological condition caused by the low partial pressure of oxygen at high altitudes, resulting in insufficient oxygen in the blood and tissues, causing climbers to feel weak and unable to think clearly.

Vapour Pressure

The pressure exerted by the vapours above a liquid when both the vapour and liquid phases are in dynamic equilibrium inside a closed vessel at a given temperature.

Raoult's Law (for Volatile Liquids)

A law stating that for a solution of volatile liquids, the partial vapour pressure of each component is directly proportional to its mole fraction in the solution: $p_i = x_i p_i^0$.

Ideal Solution

A liquid-liquid solution that obeys Raoult's law over the entire range of concentration, showing no heat exchange on mixing ($\Delta_{\text{mix}}H = 0$) and no change in total volume ($\Delta_{\text{mix}}V = 0$).

Non-Ideal Solution

A solution that does not obey Raoult's law across the entire concentration range, exhibiting vapour pressures higher or lower than those predicted by Raoult's law.

Positive Deviation from Raoult's Law

A behavior of non-ideal solutions where observed vapour pressure is higher than predicted because solute-solvent ($A\text{--}B$) attractions are weaker than pure component ($A\text{--}A$, $B\text{--}B$) attractions, resulting in $\Delta_{\text{mix}}H > 0$ and $\Delta_{\text{mix}}V > 0$.

Negative Deviation from Raoult's Law

A behavior of non-ideal solutions where observed vapour pressure is lower than predicted because solute-solvent ($A\text{--}B$) attractions are stronger than pure component ($A\text{--}A$, $B\text{--}B$) attractions, resulting in $\Delta_{\text{mix}}H < 0$ and $\Delta_{\text{mix}}V < 0$.

Azeotrope

A binary liquid mixture that boils at a constant temperature and distils without change in composition, having identical liquid and vapour compositions such that components cannot be separated by fractional distillation.

Minimum-Boiling Azeotrope

An azeotropic mixture formed by solutions exhibiting large positive deviations from Raoult's law that boils at a temperature lower than either of its pure components (e.g., ethanol-water at $\sim 95\%$ ethanol by volume).

Maximum-Boiling Azeotrope

An azeotropic mixture formed by solutions showing large negative deviations from Raoult's law that boils at a temperature higher than either of its pure components (e.g., $68\%$ nitric acid and $32\%$ water by mass, boiling at $393.5\,\text{K}$).

Colligative Properties

Properties of dilute solutions that depend strictly on the total number of solute particles relative to the total number of particles present, irrespective of the nature or identity of the solute.

Relative Lowering of Vapour Pressure (RLVP)

The ratio of the decrease in solvent vapour pressure upon dissolving a non-volatile solute to the vapour pressure of the pure solvent: $\frac{p_1^0 - p_1}{p_1^0} = x_2$.

Molal Elevation Constant ($K_b$ / Ebullioscopic Constant)

The elevation in boiling point produced when $1\,\text{mol}$ of a non-volatile solute is dissolved in $1\,\text{kg}$ of a solvent, expressed in $\text{K}\,\text{kg}\,\text{mol}^{-1}$.

Molal Depression Constant ($K_f$ / Cryoscopic Constant)

The depression in freezing point produced when $1\,\text{mol}$ of a non-volatile solute is dissolved in $1\,\text{kg}$ of a solvent, expressed in $\text{K}\,\text{kg}\,\text{mol}^{-1}$.

Semipermeable Membrane (SPM)

A continuous sheet containing a network of submicroscopic pores that allows small solvent molecules to pass through while blocking larger solute particles.

Osmosis

The spontaneous net flow of solvent molecules through a semipermeable membrane from pure solvent (or a dilute solution) into a more concentrated solution.

Osmotic Pressure ($\Pi$)

The excess hydrostatic pressure that must be applied to the solution side across a semipermeable membrane to just prevent the influx of solvent: $\Pi = CRT$.

Isotonic Solutions

Two solutions having identical osmotic pressures at the same temperature, resulting in no net movement of solvent across a semipermeable membrane between them.

Hypertonic Solution

A solution possessing a higher solute concentration and higher osmotic pressure than cellular fluid (e.g., salt concentration $> 0.9\,\%(w/V)\;\text{NaCl}$), causing water to flow out of cells and making them shrink.

Hypotonic Solution

A solution possessing a lower solute concentration and lower osmotic pressure than cellular fluid (e.g., salt concentration $< 0.9\,\%(w/V)\;\text{NaCl}$), causing water to flow into cells and making them swell.

Edema

Tissue puffiness and swelling caused by water retention in tissue cells and intercellular spaces due to osmosis, often triggered by consuming excess dietary salt.

Reverse Osmosis (RO)

A non-spontaneous process where pure solvent is forced out of a solution across a semipermeable membrane into pure solvent by applying an external pressure larger than the osmotic pressure ($P > \Pi$).

Abnormal Molar Mass

A molar mass value determined from colligative properties that is either lower (due to solute dissociation) or higher (due to solute association) than the theoretical or expected molecular mass.

van 't Hoff Factor ($i$)

A dimensionless factor accounting for the extent of dissociation or association of a solute, defined as the ratio of normal molar mass to abnormal molar mass, or observed colligative property to calculated colligative property.