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Topic 2: States of matter and mixtures

3 dot points across 3 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How does paper chromatography separate a mixture, and what does an Rf value tell us?

Paper chromatography and Rf values: how chromatography separates a mixture, the core practical investigating inks, calculating Rf values, and identifying substances from a chromatogram.
A focused answer to Edexcel GCSE Chemistry topic 2, covering how paper chromatography separates a mixture using a stationary and mobile phase, the core practical investigating the composition of inks, calculating and interpreting Rf values, and using chromatograms to identify substances and judge purity.
9 min answer →

How do we tell pure substances from mixtures and separate the components?

Mixtures and separation: pure substances and mixtures, the separation techniques (filtration, crystallisation, simple and fractional distillation), and producing potable water.
A focused answer to Edexcel GCSE Chemistry topic 2, covering the difference between pure substances and mixtures, how purity affects melting and boiling points, filtration, crystallisation, simple and fractional distillation, choosing the right technique, and producing potable water.
9 min answer →

How does the particle model explain the three states of matter and the changes between them?

States of matter: the particle model of solids, liquids and gases, the changes of state and their names, state symbols, and the limitations of the simple particle model.
A focused answer to Edexcel GCSE Chemistry topic 2, covering the particle model of solids, liquids and gases, the arrangement, movement and energy of particles, the names of the changes of state, how to predict the state at a given temperature, and the limitations of the simple particle model.
9 min answer →