Instrumental methods of analysis
Instrumental methods of analysis rely on machines. There are several different types of instrumental analysis. Some are suitable for detecting and identifying A substance made of one type of atom only., while others are better suited to A substance formed by the chemical union of two or more elements.. Data can be automatically recorded.
Compared to simple laboratory tests, instrumental methods of analysis may give improved:
- speed (they are quick)
- accuracy (they reliably identify elements and compounds)
- sensitivity (they can detect very small amounts of a substance in a small amount of sample)
The disadvantage is that analytical instruments are very expensive so tests using laboratory glassware are cheaper and more readily available.
Identifying metal ions
A flame photometer can be used to identify metal ions. The coloured light from a To turn from a liquid to a gas or a vapour. sample can be split to produce an Light given off by a substance, split into its component colours or wavelengths.. The different lines in an emission spectrum look like a coloured barcode. Each Shiny element that is a good conductor of electricity and heat, and which forms basic oxides. Electrically charged particle, formed when an atom or molecule gains or loses electrons. produces a unique emission spectrum.
The metal present in a sample is identified by comparing its A series of similar waves arranged in order of wavelength or frequency. with reference spectra. These are emission spectra from known metal ions. If two spectra match, they must be from the same metal ion.
Emission spectroscopy
An emission spectrometer analyses the spectrum from a hot sample. It can record the exact The length of a single wave, measured from one wave peak to the next. of the light that is emitted by the sample.
It can then match the pattern and wavelengths to reference data for known elements.
Emission spectroscopy is used to analyse substances in the steel industry and also to identify elements in stars.