A physical property of a substance is a characteristic that can be observed or measured without changing the substance. Physical properties include color, density, hardness, and melting and boiling points.
A chemical property, however, describes how the substance interacts or does not interact with other substances to change into to new substances, in other words, undergo a chemical change.
Let me give you an example with carbon dioxide.
Have you ever felt a stinging sensation in your nose when burping after drinking a carbonated (fizzy) drink?
Well this is because CO₂ reacts with water lining the nasal passage to form a weak acid called carbonic acid. Carbonic acid is the reason why fizzy drinks taste sour and why burping when drinking fizzy drinks causes a painful sting inside the nasal passage. Now this is a chemical change because carbon dioxide has reacted with water to change into something totally new, carbonic acid.

View the video on the right.
1. Identify three physical properties of CO₂ that can be identified from the video.

2. Identify one chemical property of CO₂.

You can perform this demostration at home with parental supervision.

We will now use one particular physical porperty of CO₂ to perform the next demonstration.

For the bubble challenge you will need the items shown on the right. A bubble maker from the novelty store, Baking soda, vinegar and a large glass mixing bowl.

Place 3 teaspoons of baking soda in the bowl and add a glass of vinegar. Notice how the gas quickly forms, this gas is carbon dioxide.

Carbon dioxide is denser then air and so it accumulates inside the bowl.

Blow soap bubble in the bowl and see which is the biggest bubble that can be trapped suspended above the surface of the liquid.

By video taping the bubbles you may notice some weird behaviour.

What is one physical property of carbon dioxide that is visible here in this demonstration?