Science Chemistry Topics Flashcards

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

Answer: Wood burning to produce ash and smoke

Burning wood produces ash and smoke — entirely new substances are formed, which is the defining feature of a chemical change.

What term describes the process when water vapour cools and turns back into liquid water?

Answer: Condensation

Condensation is the process where water vapour loses heat energy and changes back into liquid water.

Which state of matter has both a definite shape and a definite volume?

Answer: Solid

Solids have tightly packed particles that give them a fixed shape and volume that does not change with the container.

Which of the following is NOT a physical change?

Answer: Iron rusting when exposed to water

Iron rusting is a chemical change because a new substance — iron oxide (rust) — is formed.

When a solid changes directly into a gas without passing through the liquid state, this process is called:

Answer: Sublimation

Sublimation is when a solid turns directly into a gas — dry ice (solid carbon dioxide) is a classic example.

Which statement best describes particles in a liquid?

Answer: Particles are close together but can flow and move past each other

In a liquid, particles are close together but have enough energy to flow and move past one another, giving liquids a definite volume but no fixed shape.

Heating water in a pot until it boils and produces steam is an example of:

Answer: A physical change, because the water molecules are unchanged

Boiling water is a physical change — steam is still made of water molecules, just in a gaseous state, and can be condensed back to liquid water.