Mixtures and Solutions

Get seated. Get out notebooks and begin notes. Mixtures and Solutions A mixture is a combination of two or more components that are NOT chemically combined, and retain their identities. Mixtures can be physically separated. The identities of the substances DO NOT change. A homogeneous mixture is also called a solution.

Mixtures When a mixture’s components are easily recognizable, such as pizza, it is called a heterogeneous mixture. In a homogeneous mixture such as chocolate milk, the component particles cannot be distinguished, even though they still retain their original properties.

Mixtures Common Techniques for Separating Mixtures Distillation – separates a mixture based on boiling points of the component. Examples : saltwater crude oil into gasoline and kerosene Magnet – separates iron from other objects. Centrifuge – spins and separates according to densities.

Solutions A mixture that appears to be a single substance but is composed of particles of two or more substances that are distributed evenly amongst each other. A solution may be liquid, gaseous, or solid. Examples of solutions Liquid - seawater Gas - air Solid - alloys

Parts of a Solution SOLUTE – the part of a solution that is being dissolved (usually the lesser amount) SOLVENT – the part of a solution that dissolves the solute (usually the greater amount) Solute + Solvent = Solution Solute liquid Solvent solid Example Mercury in gold, Hexane in wax Steel, Brass’ Alloys, gas Hydrogen into metals Sugar, Salt, Tea, Kool-Aide Mixed drinks, Paint thinners. Soft drinks****, oxygen in water. Gas Air

Solutions Dissolving – The process in which particles of substances separate and spread evenly amongst each other. Solute – substance that is dissolved. A solute is soluble, or able to dissolve. A substance that is insoluble is unable to dissolve, forms a mixture that is not homogeneous, and therefore NOT a solution. Solvent – substance in which solute is dissolved.

Definitions Solutions can be classified as saturated or unsaturated or super-saturated. A saturated solution contains the maximum quantity of solute that dissolves at that temperature. An unsaturated solution contains less than the maximum amount of solute that can dissolve at a particular temperature

Definitions SUPERSATURATED SOLUTIONS contain more solute than is possible to be dissolved Supersaturated solutions are unstable. The supersaturation is only temporary, and usually accomplished in one of two ways: Warm the solvent so that it will dissolve more, then cool the solution Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution.

Solubility The solubility of a solute is the amount of solute needed to make a saturated solution using a given amount of solvent at a certain temperature. Solubility is usually expressed in grams of solute per 100 ml of solvent (g/100ml) Three (3) methods that affect solubility Mixing, stirring, or shaking Heating Crushing or grinding

Suspension A mixture in which particles of a material are dispersed through- out a liquid or gas but are large enough that they settle out. Particles are insoluble, so they DO NOT dissolve in the liquid or gas. Particles can be separated using a filter. Examples: Salad dressing Medicines that say “shake well before use”

Colloids A mixture in which the particles are dispersed throughout but are not heavy enough to settle out. Made up of solids, liquids and gases. Examples : Mayonnaise Stick deodorant milk

Tyndall Effect The Tyndall effect, also known as Tyndall scattering, is light scattering by particles in a colloid or else particles in a very fine suspension. Flour suspended in water appears to be blue because only scattered light reaches the viewer and blue light is scattered by the flour particles more than red.