4.8 Chemical analysis

Unit Summary

This Chemical Analysis unit is aligned with the AQA GCSE Chemistry specification and is designed for flexible sequencing. It assumes that students have built a solid foundation of substantive and disciplinary knowledge from earlier chemistry units, such as particle theory, separation techniques, chemical reactions, and atomic structure. The unit develops both scientific content and working scientifically skills in a coherent and applied context.

The substantive content includes the distinction between pure substances and mixtures, the formulation of useful products such as medicines and fuels, and the identification of unknown substances using a range of analytical techniques. Students explore qualitative tests for common gases and ions, such as flame tests, sodium hydroxide precipitate tests, and tests for carbonates, halides, and sulfates. They also learn how to separate mixtures using paper chromatography and how to interpret chromatograms. The unit further includes knowledge of instrumental methods, with a focus on flame emission spectroscopy, emphasising its benefits in industrial and forensic contexts.

Disciplinary knowledge is developed through practical activities that promote skills such as hypothesis testing, observation, recording accurate results, analysing data, and evaluating experimental methods. Students conduct flame tests, test for ions, and use chromatography to identify components of mixtures, helping them link theory to tangible laboratory work.

Assessment for Learning (AfL) strategies are embedded throughout the unit to support knowledge retention and address misconceptions—such as confusion between pure substances and chemically pure compounds, or misinterpretation of chromatograms. Retrieval practice, diagnostic questioning, and structured analysis tasks support deeper understanding and progression.

This unit extends students’ scientific thinking by connecting analytical chemistry to real-world applications and STEM careers. Through case studies and contextual examples—from environmental monitoring to medical testing—students understand how chemical analysis plays a critical role in areas such as pharmaceuticals, forensic science, and industrial quality control. This approach encourages aspiration, curiosity, and a broader appreciation of the relevance of chemistry beyond the classroom.