Physical and Chemical Changes Lesson 5 Unit 2

READING GUIDE FOR LESSON 5 Essential Question: How do physical and chemical changes to matter compare? Vocabulary: Physical change Chemical change Precipitate

WHAT ARE PHYSICAL CHANGES? A physical change alters the form of an object without changing what type of matter it is. Changes in size and shape are examples of physical changes. The changing states of matter are physical changes. As long as the substance does not changes its chemical identity, it is going through a physical change. Solutions are physical changes because the substances do not change their identity.

WHAT ARE PHYSICAL CHANGES?

What Are Chemical changes? A chemical change is a change in matter in which the substances that make up the matter change into other substances. For example, when brownies batter bakes, a chemical change occurs. Substances that undergo a chemical change no longer have the same properties because they no longer have the same identity. This is because the atoms in the substances that have formed are arranged differently from the original substance.

What Are Chemical changes?

What are signs of chemical change? A color change is one clue that a chemical change has taken place. When iron rust, it changes from gray to reddish brown in color. Another sign of a chemical change is the release or the absorption of energy. This energy could be in form of light, heat, or sound. If substances get warmer or cooler or if they give off light or sound, it is likely that a chemical change has happened. The formation of a gas is another sign that a chemical change has happened. Some chemicals produce a precipitate. This is a solid that sometimes forms when two liquids combine.

What are signs of chemical change?

How do physical and chemical changes compare? Physical and chemical changes take place everyday all around us. There are ways to determine the type of change it can be by seen how easily the change is reversed. Many physical changes can be reversed easily. Chemical changes are not reversed easily. Another way to determine the type of change is to study the chemical properties before and after the change. If they have different chemical properties, then substances have undergone a chemical change.

How do physical and chemical changes compare?

How do physical and chemical changes compare?

HOMEWORK In groups of two or three prepare and present a brief demonstration that illustrates the differences between a physical change and a chemical change. The presentation should include an explanation on the differences between a physical change and a chemical change. It should also include a visual aid and a demonstration.