Physical and Chemical Changes

If we have any substance, it can be concluded that a chemical change has happened if--

• there is a gas produced

• the state of matter changes

• there is a decrease in mass

• the matter is stirred thoroughly

Which of the following would indicate the formation of a new substance?

• A liquid turns to a solid

• A sample of metal melts

• Bubbles and fizzing occur

• A solid dissolved in a liquid

Answer explanation

fizzing is a sign that gas is being produced

Which of the following is an example of a physical change?

• An explosion

• A solid stays a solid

• A piece of paper is crumpled

• Two liquids are mixed and it warms up

Answer explanation

The paper is still paper! The composition of the paper does not change.

When two liquids are mixed, the container feels colder to the touch. This is evidence of what?

• A physical change

• A chemical change

• A state of matter change

• No change

Answer explanation

In this example, the state of matter doesn't change, only the temperature changed.

When two liquids are mixed, the color and temperature stay the same. This is evidence of what?

• A physical change

• A chemical change

• A state of matter change

• No change

Which of the following is an example of a chemical change that occurs in your home?

• water boiling on the stove

• milk going sour

• smashing a window with a baseball

• adding food coloring to icing for a cake

Answer explanation

The milk begins to form solid chunks when it goes sour

Evidence of a chemical change can be observed when–

• a solid melts into a liquid

• cookies are crumbled

• a drink is poured from a can to a cup

• a banana turns brown after being cut