Reversible reactions in a sealed container
2 marks · EasyThe thermal decomposition of solid ammonium chloride is a reversible reaction.
Explain why both ammonia and hydrogen chloride gases are observed inside the sealed tube during heating, and why a white solid appears again above the heated area.
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Marking points
M1 · 1 mark · Describes that ammonium chloride decomposes to form ammonia and hydrogen chloride gases when heated.
M1 · 1 mark · Explains that these gases recombine at the cooler part of the tube to form a white solid (ammonium chloride).
Worked solution
When heated, ammonium chloride decomposes into ammonia and hydrogen chloride gases:
These gases travel to the cooler part of the tube, where they react together to form solid ammonium chloride again:
This results in both gases inside the tube during heating and a white solid forming above the heated area.