Introduction to Mixtures, Lecture notes of Chemistry

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Introduction

to Mixture

Direction: Observe the pictures

below.

MIXTURES

Are made of eithers or compounds

that are physically combine. Thus,

the components of mixtures can be

separated physically as well.

Mixtures can be classified according

to how they are combined.

• In chemistry, a mixture forms when two or

more substances are combined such that each substance

retains its own chemical identity. Chemical bonds between

the components are neither broken nor formed. Note that

even though the chemical properties of the components

haven't changed, a mixture may exhibit new physical

properties, like boiling point and melting point. For example,

mixing together water and alcohol produces a mixture that

has a higher boiling point and lower melting point

than alcohol (lower boiling point and higher boiling point

than water).

Homogeneous mixture

• Has uniform composition all throughout
• Homogeneous mixtures can be defined as the

mixtures which possess the same properties and

combination throughout their mass.

• Examples: alloys, salt, and water, alcohol in water,

etc.

Heterogeneous

mixture

• is not uniformly combined because it shows two

or more distinct phases of matter

• Heterogeneous mixtures possess different

properties and compositions in various parts i.e.

the properties are not uniform throughout the

mixture.

• A solution is composed of two or

more substances that are evenly

mixed. Most solutions allow light to

pass through. A solution is

considered a homogeneous

mixture. You can separate solutions

through distillation or sublimation.

A chemical solution contains very small

particle sizes (less than 1 nanometer in

diameter). A solution is physically stable and

the components cannot be separated by

decanting or centrifuging the sample.

Examples of solutions include air (gas),

dissolved oxygen in water (liquid), and

mercury in gold amalgam (solid), opal

(solid), and gelatin (solid).

• Particles in a suspension are often large enough that

the mixture appears heterogeneous. Stabilizing agents

are required to keep the particles from separating.

Like colloids, suspensions exhibit the Tyndall effect.

Suspensions may be separated using either

decantation or centrifugation. Examples of

suspensions include dust in air (solid in gas),

vinaigrette (liquid in liquid), mud (solid in liquid), sand

(solids blended together), and granite (blended

solids).

A colloid mixture is a heterogeneous

mixture composed of scattered particles

that cause Tyndall effect, wherein light

gets scattered in all directions. A good

example of a colloid is a fog. Fog

particles are scattered, allowing a beam

of light passing through the fog to be

scattered as well.

Characteristics of Mixtures

The constituents of a mixture are not

present in a fixed ratio. The various

characteristics of mixtures are discussed

below.

There is no chemical force acting between

the two or more substances that are mixed,

but they still exist together.

They can either be heterogeneous or

homogeneous in nature.

The proportions of the substances vary in an

indefinite manner.

The properties of the mixture depending

upon the individual components.

The constituents of the mixture can be

separated by physical methods.

It can be concluded that almost

everything in our vicinity is nothing but a

mixture. For example, the food we eat is

a mixture of ingredients, the

atmospheric air we breathe is a

combination of gases and the fuel we

use in locomotives is a heterogeneous

mixture.

Examples of Mixtures

Crude oil : A mixture of organic compounds

(mainly hydrocarbons)

Seawater : A mixture of various salt and

water.

Air : a mixture of various gases like oxygen,

carbon dioxide, nitrogen, argon, neon, etc.

Ink : A mixture of coloured dyes.