Transition metal introduction to colour
- Created by: une-meduse
- Created on: 12-05-13 19:27
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- Transition Metal Colour determination
- Factors affecting colours
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The colour of a transition metal compound is determined by the difference in energy between its d orbitals
- Size and type of ligand
- Strength of metal-ligand bonds
- Complex shape
- Co-ordination number
- Oxidation state
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The colour of a transition metal compound is determined by the difference in energy between its d orbitals
- Determining concentration
-
Ultraviolet–visible spectroscopy can be used to determine the concentration of a transition metal complex solution
- It passes different frequencies of light through a sample
- The amount of light absorbed is proportional to the concentration of the absorbing species
- A number of solutions of complex are made up to known conc and placed in a spectrometer
- Different frequencies of light are directed, and absorbance at each frequency is measured - the highest absorbency is plotted on a calibration graph
- A solution of known concenteations tested in turn for max absorbance at the relevant wavelength
- These are recorded on a graph: max absorbance v conc
- Unknown conc tested, marked on graph and estimated concentrationis read off the graph
- These are recorded on a graph: max absorbance v conc
- A solution of known concenteations tested in turn for max absorbance at the relevant wavelength
- Different frequencies of light are directed, and absorbance at each frequency is measured - the highest absorbency is plotted on a calibration graph
- It passes different frequencies of light through a sample
- A colorimeter can also be used to measure the concentration of a complex ion solution
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Colorimeters only measure the absorbance of a specific frequency of light rather than the spectrum measured by UV-Vis spectrometers
- They basically work in the same way as ultraviolet visible spectroscopy
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Colorimeters only measure the absorbance of a specific frequency of light rather than the spectrum measured by UV-Vis spectrometers
- If accurate quantitative determination of the concentration of the solution is difficult, the ligand may be replaced to change its colour and increase its absorbance
-
Ultraviolet–visible spectroscopy can be used to determine the concentration of a transition metal complex solution
- Factors affecting colours
- A number of solutions of complex are made up to known conc and placed in a spectrometer
- Different frequencies of light are directed, and absorbance at each frequency is measured - the highest absorbency is plotted on a calibration graph
- A solution of known concenteations tested in turn for max absorbance at the relevant wavelength
- These are recorded on a graph: max absorbance v conc
- Unknown conc tested, marked on graph and estimated concentrationis read off the graph
- These are recorded on a graph: max absorbance v conc
- A solution of known concenteations tested in turn for max absorbance at the relevant wavelength
- Different frequencies of light are directed, and absorbance at each frequency is measured - the highest absorbency is plotted on a calibration graph
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