Essay

MODULE 3

CHANGES IN MATTER

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Every minute and hour of the day, changes takes place in all the living things that are around and within us. A lot of changes occur in land, in water, and air. Water evaporates from lakes, rivers, seas, and oceans. Mineral deposits in land are formed through chemical changes occurring underneath the earth. Many undesirable pollutants in air are formed through chemical changes.

At home, countless changes happen all the time. You dissolve sugar in hot water to prepare coffee or milk. Ice melts when out of the freezer. Water boils and evaporates. All these are typical physical changes.

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At the end of this module, students should be able to:

1. differentiate physical and physical change;

2. write chemical equation from word equation;

3. classify chemical reactions as to combination, decomposition, single replacement, and double replacement;

4. balance chemical equations ; and

5. distinguish the laws governing chemical changes.

LESSON 3.1 – PHYSICAL AND CHEMICAL CHANGES

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Substances can exists in three different states of matter: solids, liquids, or gases. A substances can change from one state of matter to another. Changes in matter can occur as a result of temperature or pressure changes. Changes in matter can be classified as either physical changes or chemical changes.

Lesson 3.1.1 Physical Change

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Physical change is a change of state in which the physical appearance is changed but not the intensive property and the identity of the substance is retained. A physical change is a change in size, shape, or state of matter. It does not involve the creation of something new.

EXAMPLE 3- 1

1. melting of ice cubes

Ice melts because of the absorption of heat from the surrounding. Heating alters only the...