A2- Transition Metals; colours
No description yet. This curated deck is ready for daily study.
Card preview (9)
Write an equation that links energy, frequency and the Plank constant
E = hf
Write an equation that links energy, c, wavelength and the Plank constant
E = hc/λ
Explain (briefly) why copper (II) sulfate solution is blue
absorbs other parts of the visible spectrum, reflects/transmits blue light
Explain why transition metal ions absorb light in the visible part of the spectrum. You should refer to electron transitions in your answer
• d sub-shell orbitals have a ground and excited state • electrons absorb light photons with energy equivalent to visible light (E= hf) • promoted to excited state • relax back an release thermal energy • light not absorbed is reflected
Give 3 factors that affect the colour of a transition metal
• coordination number • ligands • oxidation state
Explain why [CuCl4]2- has a different colour to [Cu(H2O)6]2+
• different ligands and co-ordination number • changes the energy gap between ground and excited state d sub-shell orbitals • different frequency of light absorbed [E = hf)
Explain why Cu+ ions do not form coloured solutions
do not have an INCOMPLETE d-subshell
What can colorimetry be used to determine?
concentration of coloured ions
How is colorimetry carried out to find concentration of coloured ions?
1) series of dilutions, with known concentrations 2) find absorbance using colorimeter 3) plot graph of absorbance vs conc and draw line of best fit 4) find absorbance of unknown sample 5) use graph