Question
Explain, giving one example of the following chemical change:
Thermal dissociation
Thermal dissociation
✓
Answer
A reversible decomposition reaction brought about only by heat is called thermal dissociation reaction. Heat some solid ammonium chloride in a test tube. Two colourless gases, ammonia and hydrogen chloride, are produced. As these gases move up to the upper part of the cooler test tube, they combine to form ammonium chloride, which appears as a white sublimate on the upper cooler side o the test tube.
$ \mathrm{NH}_4 \mathrm{Cl} \rightleftharpoons \mathrm{NH}_3 \uparrow+\mathrm{HCl} \uparrow $
$ \mathrm{NH}_4 \mathrm{Cl} \rightleftharpoons \mathrm{NH}_3 \uparrow+\mathrm{HCl} \uparrow $
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