Pure Substances and Mixtures - Lecture Notes Review

Flashcards covering key concepts from the lecture notes on pure substances, mixtures, elements, compounds, filtration, and alloys.

What defines a pure substance?

A pure substance has uniform and definite composition and cannot be separated into simpler substances by physical means.

Can a pure substance be separated into simpler substances by physical means? Give an example.

No. Pure substances cannot be separated by physical means; for example, water cannot be split into hydrogen and oxygen by filtration or simple distillation.

What is a homogeneous mixture and how can its composition vary?

A homogeneous mixture has a uniform composition, but the amount of each component can vary in different samples (e.g., copper sulfate solutions with different concentrations show different colour intensities).

What is filtration used for in mixtures?

Filtration is a method to separate a solid from a liquid by passing the mixture through filter paper (often folded filter paper or a cone).

What is an element?

An element is a basic form of matter that cannot be broken down into simpler substances by chemical means.

What is a compound?

A compound is a chemical substance made up of two or more elements that are chemically bound together in a fixed ratio.

Give examples of elements.

Examples include sodium, iron, copper, gold, silver, hydrogen, and oxygen.

Name examples of pure substances in different states of matter.

Solids: iron, copper, gold, silver; liquid: bromine; gases: oxygen, hydrogen.

What is an alloy?

An alloy is a substance formed by combining two or more elements, typically metals, to improve properties.