As a final test we reproduced the thermochromic shift in the UV
visible spectra of CoCl2 solutions of water and propan-2-ol, which
arise due to the different absorbance spectra of cobalt chloride
complexes in tetrahedral or octahedral geometries. In the tetrahedral
arrangement these complexes are pink in colour and in the
octahedral form these complexes are blue in colour. In solutions of
water and propan-2-ol, a temperature-dependence exists whereby
the tetrahedral form, stable at low temperature, exists in equilibrium
with the octahedral form, favoured at higher temperature