States of Matter

There are just three states of matter that are possible: liquid, solid, and gas. Changes in pressure, composition, or temperature may result in a chang of state.

The Macroscopic Definitions are:

 

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1. What are possible states of matter?

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2. Air, vodka and brass are examples of ...

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Next lesson: Work, Heat and Energy

Video Transcript

Gas -Gas doesn’t have a definite volume or shape and is easily compressible

Liquid – Liquids have a constant volume, not a definite shape, and are slightly compressible

Solid – Solids have definite volumes and shapes, and are rigid and very difficult to compress

The Microscopic Definitions are:

Gas – In gas, the molecules are far apart and they move rapidly and frequently while colliding with the other molecules

Liquid – In liquids, the molecules are close together (even touching one another) but they’re still moving, and the arrangement of the neighboring molecules is changing rapidly.

Solid – In solids, all molecules are held in place rigidly and the neighboring molecules may change just very slowly or often, they’re not changing at all.

Classification of Matter

All of our Earth’s matter is classified as either a pure substance or a mixture, and a mixture can be heterogeneous or homogeneous. Pure substances may either be compounds or elements.

We cannot separate Pure Substances into component parts through physical methods. So we follow the constant composition law. The basic reason behind this sort of properties lies in the fact that pure substances are containing just one single molecule type.

We can divide Pure Substances into two main categories:
Elements – Elements are containing just one atom type
Compounds – Compounds are containing more than just one atom type

But there are exceptions. These include:
Elements – Gold (Au), Oxygen (O2), Diamond (C), Silicon (Si)
Compounds – Ethanol (C2H6O), Water (H2O), Quartz (SiO2)

Mixtures are having variable compositions and may be separated by physical methods into component parts. Mixtures are containing more than just one molecule type.

Mixtures may as well be divided into two main categories:

Homogeneous – The properties and composition of these mixtures are uniform
Heterogeneous – These mixtures have non-uniform properties and composition

We call homogeneous solutions also solutions. Most people, when hearing the word solution, are thinking of liquids. In fact, though, solutions may occur in all states of matter, solid, liquid, and gas.

Examples are including:

Air – the principal components of air include N2, O2 & CO2
Vodka – The principal components of Vodka are water and ethanol
Brass – Brass is a solid solution of Zn and Cu
Ruby – Ruby is a solid solution of Cr2O3 and Al2O3
To get an idea of the “variable composition” principle, just think of one of the differences between Everclear (5% Water and 95% Ethanol) and Vodka (some 60% Water and 40% Ethanol).

Both these compositions are homogeneous mixtures of ethanol and water, but there’s a huge difference in the concentration of ethanol between the two compositions.

Unlike the situation in solutions, the heterogeneous mixture composition is varying from point to point.

Some examples are including:
Wood, Concrete, Chocolate chip cookies, and Rocks

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