Changing Conditions - Heat & Water Effects
Chemistry: Cambridge International GCSE Supplement, topic 6.3.4
Changing Conditions: Heat and Water Effects
Reversible reactions go forward and backwards. Heat removes water, forming anhydrous compounds. Adding water reverses this, forming hydrated compounds.
What are reversible reactions?
- Reversible reactions can go forward and backwards.
- Conditions like heat and water can change reaction direction.
- Copper(II) sulfate and cobalt(II) chloride show clear reversible reactions.
Heating hydrated compounds
- Heating hydrated copper(II) sulfate removes water, forming anhydrous copper(II) sulfate.
- Hydrated copper(II) sulfate is blue; anhydrous form is white.
- Heating hydrated cobalt(II) chloride removes water, changing pink crystals to blue powder.
- Heat causes water to leave, shifting the reaction towards anhydrous form.
Adding water to anhydrous compounds
- Adding water to white anhydrous copper(II) sulfate makes it blue hydrated copper(II) sulfate.
- Adding water to blue anhydrous cobalt(II) chloride changes it back to pink hydrated crystals.
- Water addition shifts the reaction towards the hydrated form.
- This change is reversible by heating or adding water.
Test yourself on Changing Conditions - Heat & Water Effects
What is a defining characteristic of a reversible reaction?