Question 16
[Maximum number: 1]
Anhydrous cobalt(II) chloride is blue and turns pink when water is added.
How is this reaction reversed?
A
adding dilute acid
B
filtering
C
heating
D
cooling
CAIE IGCSE Chemistry Reversible Hydration of Salts
Practise predicting and reversing hydration changes in copper sulfate or cobalt chloride by heating hydrated salts or adding water to anhydrous salts.
How this is tested
- use heating to remove water from a hydrated salt and form its anhydrous colour
- add water to the anhydrous salt to restore the hydrated form and reverse the change
- identify blue-to-white copper sulfate and pink-to-blue cobalt chloride changes correctly