Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Matter is anything that has mass and takes up space. All matter is made of tiny particles that are constantly in motion.
Solids: Have a fixed shape and a fixed volume. The particles are packed very tightly together and can only vibrate in place. Examples include ice ( in solid form) and wood.
Liquids: Have a fixed volume but take the shape of their container. The particles are close together but can slide past one another. Examples include liquid water () and oil.
Gases: Have no fixed shape or volume; they expand to fill whatever container they are in. The particles move very fast and are far apart. Examples include steam ( as a gas) and oxygen ().
Changes in state are physical changes caused by adding or removing heat. For water, the freezing point is and the boiling point is .
The process of a solid turning into a liquid is called melting, and a liquid turning into a gas is called evaporation or boiling.
📐Formulae
💡Examples
Problem 1:
You have a sealed balloon filled with air. If you squeeze the balloon, the volume of the air inside decreases. Which state of matter is inside the balloon, and why can it be compressed?
Solution:
The state of matter is a Gas.
Explanation:
Gases do not have a fixed volume because there is a lot of empty space between the particles. This allows the particles to be pushed closer together (compressed) when pressure is applied.
Problem 2:
If you place of liquid water into a freezer until it reaches , what state of matter will it become?
Solution:
It will become a Solid (Ice).
Explanation:
Since the freezing point of water is , any temperature below this, such as , will cause the liquid molecules to slow down and lock into a fixed position, forming a solid.