3.18: Describe Reversible Reactions such as the Dehydration of Hydrated Copper (II) Sulfate and the Effect of Heat on Ammonium Chloride

REVERSIBLE REACTIONS: Reaction that can occur in both directions (reactants can react to form products, and products can react to form initial reactants)

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DEHYDRATION OF HYDRATED COPPER (II) SULFATE:

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DEHYDRATION OF HYDRATED COPPER (II) SULFATE

Diagram showing the Dehydration of Hydrated Copper (II) Sulfate

EXPLANATION: Copper (II) Sulfate crystals that contain Water are known as Hydrated Copper (II) Sulfate When Hydrated Copper (II) Sulfate crystals are heated in test tube, blue crystals will turn into white powder, and colourless liquid will collect at the top This is because when Hydrated Copper (II) Sulfate crystals are heated, it loses Water of Crystallisation and turns into Anhydrous Copper (II) Sulfate (white powder) and Water (colourless liquid):   CuSO4.5H2O (s)      ⇌       CuSO4 (s)     +     5H2O (l)

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EFFECT OF HEAT ON AMMONIUM CHLORIDE:

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THERMAL DECOMPOSITION OF AMMONIUM CHLORIDE

Diagram showing the Thermal Decomposition of Ammonium Chloride

EXPLANATION: When Ammonium Chloride is heated in a test tube, white crystals at the bottom disappears and reappears further up, with colourless Gas forming in between This is because heating Ammonium Chloride causes it to decompose into Ammonia (colourless gas) - NH3+, and Hydrogen Chloride - HCl:   CNH4Cl (s)      ⇌       NH3 (g)     +     HCl (g)