Instrumental analysis and flame tests: red for lithium
I can identify metal ions based on the colour of their flame tests and understand how instrumental analysis methods are used for detecting and identifying elements.
Instrumental analysis and flame tests: red for lithium
I can identify metal ions based on the colour of their flame tests and understand how instrumental analysis methods are used for detecting and identifying elements.
Lesson details
Key learning points
- Positive ions burn with distinct colours that are visible when heated above a blue Bunsen flame.
- Instrumental methods are accurate, sensitive, and rapid for detecting and identifying elements and compounds.
- Unique flame emission spectra are produced for each positive metal ion.
- A spectrometer can split light from coloured flames into flame emission spectra.
- A spectrometer can measure more than one metal ion in a single solution and the concentration of each.
Common misconception
Flame colours are unique, even in mixtures.
Explain that strong colours, like sodium's yellow, can mask others. Use spectrometry to identify masked elements.
Keywords
Flame test - A test where a chemical put into a flame produces a characteristic colour (tests for metal ions).
Spectroscope - An instrument that separates light into its component wavelengths.
Ion - An ion is an atom or group of atoms with a positive or negative charge due to the loss or gain of electrons.
Concentration - The amount of a solute dissolved in a certain volume of solvent.
Calibration curve - A graph used to determine the concentration of a substance in a sample.
Equipment
Bunsen burner setup, 'unknown' metal salt samples to do flame tests, nichrome wire loops, dilute hydrochloric acid, beakers, matches.
Content guidance
- Risk assessment required - chemicals
- Risk assessment required - equipment
Supervision
Adult supervision required
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
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