A2 Chemistry - transition metals Watch

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Report Thread starter 12 years ago
Okay this is a nightmare. I'll post a few q's.

1) When an aqueous solution of chromium(iii)chloride is evaporated at room temp, violet crystals are formed (compound X). When a hot aqueous solution of chromium(iii)chloride crystallises, pale green crystals(compound Y) are formed. When an excess of silver nitrate is added to 1 mole of eitherr of these salts a white ppt AgCl is formed. Compound X forms 3 moles of silver chloride and compound Y forms 1 mole of silver chloride. Both compounds have the same composition by mass: 19.5% chromium, 40.1% chlorine and 40.4% water.

a) calculate the empirical formula of both these salts
b) assuming that the empirical formulae are identical with the molecular formulae, what are the formulae and names of the complex cations present?
c) Why do these compounds have different colours?
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Report 12 years ago
they are coloured because in a complex with 3d orbitals, electrons can be promoted from a lower 3d orbital to an upper 3d orbital, absorbing one colour of visible light as they do so. THIS Makes the complex appear coloured.
if u still need help, PM me.

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