Define and differentiate between pure substances and mixtures. Give examples of each and explain methods of separation.

Here are the answers to your questions:

QUESTION 1: Basic

1.1) Define each term:

• 1.1.1 Pure substance: A substance that consists of only one type of matter, either an element or a compound, with a fixed chemical composition and distinct properties.
• 1.1.2 Mixture: A substance containing two or more different substances that are physically combined but not chemically bonded, retaining their individual properties.
• 1.1.3 Separation by physical means: Methods used to separate components of a mixture without changing their chemical identities, such as filtration, evaporation, or magnetism.
• 1.1.4 Separation by chemical means: Methods used to break down a compound into its constituent elements or simpler compounds by chemical reactions, which involve changing the chemical identities of the substances.

1.2) Complete the sentence:
Mixtures are separated by physical means whereas compounds are separated by chemical means.

QUESTION 2: Basic

Identify each substance as an element, a compound or a mixture:

• 2.1 Carbon dioxide gas: Compound (made of carbon and oxygen chemically bonded)
• 2.2 Air: Mixture (made of nitrogen, oxygen, argon, etc., physically mixed)
• 2.3 Sea water: Mixture (made of water, salts, and other dissolved substances physically mixed)
• 2.4 Copper metal: Element (made of only copper atoms)