Edexcel IGCSE Chemistry 1.9 Pure substances & mixtures
Practise using melting and boiling point evidence to decide whether a substance is pure or a mixture and predict impurity effects.
- Syllabus
- First assessment 2019
- Course
- Chemistry 4CH1
Exam points
- use fixed or ranged melting and boiling points to classify pure substances and mixtures
- predict how an impurity changes a melting point result or boiling range
1.9 Pure substances and mixtures question 1
[Maximum number: 3]
A student has two solids, X and Y .
One of these solids is a pure substance and the other is a mixture.
Describe how the student could identify which solid is pure and which is a mixture by measuring a physical property of each solid.
- measure the melting point
- if it has a fixed / sharp melting point, the substance is pure
- if it melts over a range of temperatures, the substance is a mixture
Allow:
- measure boiling point for M1 and substitute boiling point for melting point in M2 and boils for melts in M3
- maximum 2 marks if referring to freezing point instead of melting point
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