Question

Give two examples of chemical reactions in which heat is absorbed.

Answer 1

Endothermic reactions:
The reactions in which heat is absorbed from the surroundings to form products are called endothermic reactions.

Two examples of chemical reactions in which heat is absorbed:

1. The reaction of photosynthesis

$$\begin{gathered} 6{\mathrm{CO}}_2\left(\mathrm{g}\right)+6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\stackrel{\mathrm{Sunlight}}{\to }{\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\left(\mathrm{s}\right)+6{\mathrm{O}}_2\left(\mathrm{g}\right) \\ \mathrm{Carbon}\mathrm{dioxide}\mathrm{Water}\mathrm{Glucose}\mathrm{Oxygen} \end{gathered}$$

2. The decomposition reaction of calcium carbonate

$$\begin{gathered} {\mathrm{CaCO}}_3\left(\mathrm{s}\right)+\mathrm{heat}\to \mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right) \\ \mathrm{Calcium}\mathrm{carbonate}\mathrm{Calcium}\mathrm{oxide}\mathrm{Carbon}\mathrm{dioxide} \end{gathered}$$