Introduction

Overview. Branches Of Chemistry. Matter And States Of Matter. Pure Substances And Mixtures. Homogeneous And Heterogeneous Substances.

Take a moment to observe the world around us. The world around us is made out of many substances. For example, we see water everywhere. If we make some water cold, why does it turn into ice?.

If we want to make some water sweet, we can add some sugar into water. Then, we can stir it. After you do that, is it considered water? Then, where is the sugar? How can we get it back?.

How do scientists create pills, pesticides and other chemicals? Let us see if we can find the answers to these questions. But where should we start? Maybe, the answer lies in chemistry. Well, what is chemistry? Which branch of chemistry would be able to provide the answers to our questions.

Chemistry, is a branch of science that deals with studying the properties of matter and the changes that happen to them. We investigate elements, compounds, chemical reactions, formulas and equations, and stoichiometry.Chemistry has five major branches.These are Inorganic Chemistry, Organic Chemistry, Physical Chemistry, Analytical Chemistry and Biochemistry.

When we want to study substances with carbon-hydrogen bonds, we use Organic chemistry.Yes! Carbon is so unique that a branch of chemistry is fully dedicated to it!. This branch deals with the study of organic compounds.

On the other hand, Inorganic chemistry studies the properties and behavior of inorganic compounds.What about the other branches of chemistry such as physical chemistry, analytical chemistry, and biochemistry?.

In physical chemistry, we apply concepts of physics to chemistry. This involves the study of how concepts of physics apply to various chemical processes.

Analytical chemistry, studies how instruments and methods are used in order to separate, identify and quantify forms of matter.

Lastly Biochemistry, focuses on the chemical processes that occur within an organism.

Let us begin our journey in chemistry by defining some ideas in chemistry, like matter. What is Matter?.Matter, is something that takes up space and it has a mass.

The entire universe is made up of matter.Chemists are especially interested in various aspects of matter. They investigate the organization of matter. They are also interested in the varieties and amounts of substances that make up matter.

Is all matter the same? Does all matter behave the same?.Can matter be classified further?.Of course,.Matter, exists in three forms; solid, liquid, and gas.

Solid, is a form of matter with a fixed shape and volume.Particles are closely packed. Particles in a solid can’t move freely. They can only vibrate.They are generally not flexible. Solids cannot be compressed easily.

On the other hand liquid, is a state of matter with unfixed shape. Liquids have a fixed volume.The molecules that make up a liquid, flow easily around each other.They are kept together by attractive forces between them.Let’s say we add the liquid into a bottle. Then it assumes the shape of the bottle.

Gas, is a state of matter that has no fixed volume and shape.The molecules that make up a gas move in all directions at great speeds.They are quite distant from each other. Because of this the attractive forces between the air molecules are trivial.

Look at this illustration. The forms of matter can change from one to another. During such process, matter will maintain its’ composition. For example, upon heating, ice melts to form a liquid. Continuing the heating process, the liquid will turn to gas.

If we do it in reverse what would happen? Cooling the gas, will cause it to condense to form a liquid. If we continue the cooling process, it will freeze and form a solid.

Is there another way to classify matter? Are there ways to obtain the sugar we added to the water?.Let start with exploring how matter can be separated. There are two methods. Physical and chemical. In the physical method, there are two types. Pure substances and mixtures.

Pure substance is, matter that has definite or constant composition and distinct properties.Some examples are gold, copper, sugar, salt, hydrogen gas, and diamonds.Pure substances differ from each other, in composition. Thus, they are identified by their appearance.

How about a mixture. What is it like?.A mixture is a combination of two or more substances where the substances retain their distinct identities.Some examples are, salad, a bowl of cereal, oil and vinegar, air, soft drinks, milk.

How about coffee, Juice, and brine? Are these mixtures?.Yes.Mixtures, can be either heterogeneous or homogenous.

So, how about the sugar we added into water? After stirring it dissolves in water. Then the composition of the mixture is the same throughout the solution. This is a Homogeneous mixture. Examples are coffee, wine, air, brass, steel, natural gas, and blood.

If sand is mixed with iron filings, the sand and the iron filings remain visibly separate. This category of mixtures in which the composition is not uniform are called heterogeneous mixtures.Some examples are chocolate chip cookies, sandwich, pizza and soda with ice.

How do we separate a mixture by physical means?.Any mixture whether homogeneous or heterogeneous, can be created and separated later. This can be done using physical means to obtain the pure components. The identities of the components will not change when we do this.

To separate the iron and sand mixture, we can do the following. We can use a magnet to remove the iron filings from the sand. This happens because sand is not attracted to the magnet.

Thus the sugar we added to water can be recovered from the sugar water. We do this by heating the sugar water. When we do this, the water evaporates and gives the sugar.What happens if we make the evaporated water, cold? The water vapor will turn into water.

If a mixture, can be subdivided as homogenous and heterogeneous, how about pure substances?.Can we further classify pure substances?.