Question

What is an example of temperature change?

Answer 1

1. Some chemical reactions are characterized by changes in temperature.
2. For example, the chemical reaction between Zinc granules and dilute Sulphuric acid to produce hydrogen gas. If we touch the conical flask containing zinc granules and dilute sulphuric acid, it is found to be warm due to the rise in temperature during the reaction.
3. Similarly, in some chemical reactions in which heat energy is absorbed, the temperature falls. When Barium Hydroxide $\left[\mathrm{Ba}{\left(\mathrm{OH}\right)}_2\right]$ is added to Ammonium Chloride $\left({\mathrm{NH}}_4\mathrm{Cl}\right)$ taken in a test tube and mixed with a glass rod, then Barium Chloride (${\mathrm{BaCl}}_2$), Ammonia, and water are formed. Lots of energy is absorbed during this reaction due to which the temperature of the reaction mixture falls and the bottom of the test tube becomes very cold.