2021 · Q12
Which one of the following is an example of endothermic reaction?
general-sciencechemistry
- ACaO(s) + H2O(l) → Ca(OH)2 (aq)
- BCaCO3(s) → CaO(s) + CO2(g)
- CC(s) + O2(g) → CO2(g)
- DCH4(g) + 2O2(g) → CO2(g) + 2H2O(l)
Explanation
An endothermic reaction absorbs heat from its surroundings. The decomposition of calcium carbonate into calcium oxide and carbon dioxide requires continuous heating and so is endothermic. The other three reactions — slaking of lime, combustion of carbon and combustion of methane — all release heat and are exothermic. Hence the calcium carbonate decomposition is the endothermic example.