CAIE IGCSE Chemistry: Water of Crystallisation Question Bank

Practise using water of crystallisation in hydrated salt formulae, colour changes and heating observations for common crystals.

Exam points

define water of crystallisation as water molecules present in hydrated crystals
link heating hydrated salts to loss of water, colour change and anhydrous formulae

[Maximum number: 4]

Cobalt and copper are transition elements.

(a)

Both copper and cobalt can form coloured compounds. Some of these compounds contain water of crystallisation.

[ 4 ]

(i)

Define the term water of crystallisation.

[ 2 ]

(ii)

State the colour and formula of hydrated cobalt(II) chloride crystals.
colour
formula

[ 2 ]

M1 pink (1)

M2 $\mathrm{CoCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}$ (1)

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