a.[6]
Some complexes containing transition metal ions exhibit intense colours.
- Explain the origin of colour in transition metal complex ions.
- Identify key factors that can alter the colour of a transition metal complex.
- Describe how a student could use colorimetry to construct a calibration curve and determine the concentration of an unknown solution of a coloured complex ion.
b.[3]
Figure 1 shows the absorption spectrum of a transition metal complex ion in aqueous solution across the visible spectrum.
Use the wavelength at the maximum absorbance peak in Figure 1 to calculate the energy change, ΔE\Delta EΔE, in J, of a d-electron when it is promoted.
the Planck constant, h=6.63×10−34 J sh = 6.63 \times 10^{-34}\text{ J s}h=6.63×10−34 J s
speed of light, c=3.00×108 m s−1c = 3.00 \times 10^8\text{ m s}^{-1}c=3.00×108 m s−1