Review of Physical and Chemical Changes

What is an example of a physical change?

• Burning wood

• Rusting iron

• Melting ice

• Baking a cake

If a new substance if produced during an investigation, it is most likely due to...

• Physical change

• Chemical change

• No change occurred

• Evaporation

Students in a science class are investigating to determine if a chemical change occurs. The students mix baking soda with water in one container, baking soda with vinegar in another container, and leave a third container with just water. They carefully observe the reactions in each container. Here are the observations recorded by the group.

Based on the investigation, which bottle had a chemical change?

• Container 3 is a chemical change because there was no temperature change.

• Container 1 is a chemical change because there is no temperature change.

• Container 2 is a chemical change because there is a temperature change.

• None of the containers demonstrated a chemical change.

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

• Ice melting

• Sugar dissolving in water

• Baking a cake

• Freezing water

What happens to water particles when they are cooled?

• They vibrate more

• They speed up and move further apart

• They slow down and move closer together

• They disappear

On way to school one morning, students saw snow on the ground. On the way home, students noticed that there was less snow and a puddle of water.

Which argument best supports the claim that the snow changed to water due to the increasing temperature during the day?

• Some of the snow changed to water because the temperature rose steadily from below freezing to above freezing throughout the day.

• Some of the snow changed to water because the surrounding environment became more humid as the day progressed.

• Some of the snow changed to water because it was exposed to sunlight for an extended period of time.

• Some of the snow changed to water because the temperature dropped steadily from above freezing to below freezing throughout the day.

A candle is burning in a room. Jacob thinks a chemical change is taking place, but Maria thinks is a physical change. Who is correct and why?

• Jacob because there is heat being given off by the candle

• Maria because there is presence of a solid and a liquid.

• Both because burning the candle wick is chemical and the wax is going from solid to liquid indication a physical change.

• Neither person is correct because the candle is getting shorter.

The diagram shows three different ways that pieces of paper were changed. Which statement best describes what happened to the papers during each change?

• The papers went though physical changes because the shape changed.

• The papers went through chemical changes because the shape changed.

• The papers went though physical changes because a new substance was produced.

• The papers went through chemical changes because a new substance was produced.

A student fills a tray with water and places the tray in the freezer. Three hours later, the student removes the tray from the freezer and makes observations.

The student claims that changing the temperature of water causes a physical change that turns water into ice.

Which of the following best supports the student's claim about a physical change.

• Ice forms because heat is added, causing the particles that make up the ice to move faster. This makes the ice change shape.

• Ice forms because heat is removed, causing the particles that make up ice to move slower. This changes the water from a liquid to a solid.

• Ice forms because heat is slower, causing the particles that make up the ice to move faster. This changes the water from a liquid to a solid.

• Ice forms because heat is removed, causing the particles that make up ice to move slower. This changes the water from a liquid to a solid.

If no observable evidence of a chemical change is detected, it may mean:

• Only chemical change occurred

• Only physical change occurred

• No changes occurred

• Evidence was missed