Matter and Energy: Classifying Pure Substances and Mixtures

The video explains the categorization of matter into pure substances and mixtures. Pure substances include elements and compounds, which are chemically uniform. Mixtures are divided into homogenous and heterogeneous types, with examples provided for each. The video concludes with a review and questions to reinforce learning.

Which of the following is an example of matter?

• Light

• Sound

• Air

• Heat

What is a characteristic of pure substances?

• They are always mixtures of elements.

• They consist of only one kind of matter.

• They can be separated by physical means.

• They have variable chemical compositions.

Which of the following is a compound?

• Oxygen gas

• Carbon dioxide

• Gold

• Mercury

What happens when table salt dissolves in water?

• The sodium and chlorine atoms form ions.

• The chemical composition changes.

• It forms a new compound.

• It becomes a heterogeneous mixture.

How do compounds differ from molecules?

• Compounds are made of the same element.

• Molecules cannot be diatomic.

• Molecules are always compounds.

• Compounds consist of different elements.

What defines a homogenous mixture?

• It consists of physically discrete parts.

• It has a non-uniform composition.

• It can be separated by chemical means.

• It behaves as a single substance.

Which of the following is a homogenous mixture?

• Fruit salad

• Concrete

• Granite

• Salt water

What is a characteristic of heterogeneous mixtures?

• They are always solutions.

• They have a uniform chemical composition.

• They consist of physically separable parts.

• They cannot be separated by physical means.

Which of the following is an example of a heterogeneous mixture?

• Mud

• Bronze

• Air

• Vinegar

Which of the following is NOT a pure substance?

• Mercury

• Helium gas

• River water

• Gold