Cambridge O Level Chemistry · Syllabus 5070 · Chemistry of the Environment
Water Purity
What is Water Purity?
Water is pure when it contains only water. The evidence is physical rather than chemical: pure water has a fixed melting point of about 0 degrees Celsius and a fixed boiling point of about 100 degrees Celsius at standard atmospheric pressure. Dissolved substances lower the melting point, raise the boiling point, and cause both changes to happen over a range of temperature instead of at one value.
This definition is part of the Chemistry of the Environment chapter in Cambridge O Level Chemistry.
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