Exploring Mixtures and their Separation

Comprehensive vocabulary flashcards covering mixture classifications, concentration expressions, separation methods, and colloidal systems from Chapter 5 of Grade 9 Science.

Homogeneous mixture (Solution)

A mixture that possesses a uniform composition throughout, with solute particles smaller than $1\,\text{nm}$ in diameter that do not settle upon standing (e.g., sugar dissolved in water, vinegar, or aerated drinks).

Heterogeneous mixture

A non-uniform mixture in which the constituent substances do not blend smoothly and remain physically distinct (e.g., sand in water, oil in water, or smoke).

Solute

The substance that is dissolved by another substance to form a solution (e.g., sugar in a sugar-water solution).

Solvent

The dissolving medium in a solution that dissolves the solute (e.g., water in a sugar-water solution).

Concentration of a solution

The amount of solute dissolved in a given amount of solvent or solution.

Mass by mass percentage ($\%\,m/m$)

A concentration unit expressing the mass of solute in grams present per $100\,\text{g}$ of total solution, calculated as $\frac{\text{Mass of solute}}{\text{Mass of solution}} \times 100$.

Mass by volume percentage ($\%\,m/v$)

A concentration unit expressing the mass of solute in grams present per $100\,\text{mL}$ of solution, calculated as $\frac{\text{Mass of solute}}{\text{Volume of solution}} \times 100$.

Volume by volume percentage ($\%\,v/v$)

A concentration unit expressing the volume of solute in millilitres present per $100\,\text{mL}$ of solution, calculated as $\frac{\text{Volume of solute}}{\text{Volume of solution}} \times 100$.

Solubility

The maximum amount of solute that dissolves in a fixed quantity of solvent ($100\,\text{mL}$ or $100\,\text{g}$) at a specified temperature.

Saturated solution

A solution that cannot dissolve any additional amount of solute at a specified temperature.

Solubility curve

A graph plotting temperature on the x-axis against solubility (in grams per $100\,\text{g}$ of water) on the y-axis for one or more solutes.

Crystal

A pure solid substance composed of particles arranged in a regular, repeating geometric pattern.

Crystallization

A separation and purification technique where a hot saturated solution is cooled slowly, allowing pure solid crystals to separate out based on differences in solubility at varying temperatures.

Distillation

A method used to separate miscible liquids differing in boiling point by at least $25\,^\circ\text{C}$ (or a liquid from dissolved solids) by heating the mixture until the lower-boiling liquid vaporises and then condensing its vapour into a pure liquid.

Distillate

The pure condensed liquid collected in a receiving vessel after undergoing vaporisation and cooling during distillation.

Panga salt

A type of salt historically produced in coastal India by boiling concentrated sea brines.

Karkatch salt

A type of salt historically obtained in coastal India by the solar evaporation of sea water.

Deg-Bhapka method

A traditional distillation process passed down through generations in Kannauj, Uttar Pradesh, used to produce natural perfumes such as Mitti ka Ittar.

Fractional distillation

A distillation process used to separate components of a mixture having relatively small differences in their boiling points (less than $25\,^\circ\text{C}$), such as crude petroleum fractions.

Paper chromatography

A separation technique that separates components of a mixture based on their differing rates of movement and interactions with a paper medium and a moving solvent.

Immiscible liquids

Liquids that do not dissolve into one another and form distinct, separate layers when combined (such as oil and water).

Sublimation

The phase transition in which a substance changes directly from a solid state into a vapour state on heating (below its melting point) without passing through an intermediate liquid state.

Deposition

The phase transition in which a vapour cools and condenses directly into a solid without transitioning through a liquid state.

Alloy

A homogeneous mixture of two or more metals, or a metal and a non-metal, prepared in molten form and solidified to enhance strength, rigidity, or corrosion resistance.

Suspension

A heterogeneous mixture containing insoluble particles larger than $1000\,\text{nm}$ that remain suspended throughout the bulk medium, are visible to the naked eye, and settle over time when left undisturbed.

Centrifugation

A separation method in which a mixture is spun at high speeds, using outward centrifugal force to drive denser particles to the bottom of the container while lighter liquid stays on top.

Paperfuge

A low-cost, hand-powered centrifugation device made from paper, string, and disc components that spins blood samples rapidly without electricity to detect diseases like malaria and anaemia.

Coagulation

The process where a chemical substance (coagulant, such as powdered alum or fitkari) is added to a liquid mixture to cause fine suspended particles to clump together into larger aggregates that settle by gravity.

Colloid

A heterogeneous mixture with particle sizes between $1\,\text{nm}$ and $1000\,\text{nm}$ that remain evenly dispersed and do not settle out over time.

Tyndall effect

The phenomenon in which light is scattered by suspended particles in a colloid or suspension, making the path of the light beam visible.

Dispersed phase

The solute-like component consisting of finely distributed particles suspended throughout a colloid.

Dispersion medium

The continuous medium or substance in which the dispersed phase particles are distributed within a colloid.

Emulsion

A type of colloidal system where both the dispersed phase and the dispersion medium are liquids, categorized as oil-in-water or water-in-oil.

Dilip Mahalanabis

An Indian paediatrician who formulated and implemented Oral Rehydration Solution (ORS) therapy for treating severe dehydration caused by cholera and diarrhoea, saving millions of lives worldwide.