Question

Q). State one example each characterized by the following along with the chemical equation :
(a) Change in state
(b) Evolution of gas
(c) Change in temperature.

Answer 1

Dear Student,


(a) Change in state: The combustion reaction of candle wax (solid) melts initially to produce molten wax (liquid) and then produces carbon dioxide (gas) and water vapour (liquid). So, in this reaction, state of matter gets changed from solid to liquid and gas.


(b) Evolution of gas: When zinc granules react with dilute sulphuric acid in a flask, hydrogen gas evolves and zinc sulphate solution is formed.

${\mathrm{Zn+\; H}}_2{\mathrm{SO}}_4{\to \; ZnSO}_4{+\; H}_2\uparrow$



(c) Change in temperature: When quicklime reacts with water, slaked lime is formed with a release of large amount of heat, causing change in temperature in the reaction mixture.

$\mathrm{CaO}+{\mathrm{H}}_2\mathrm{O}\underset{}{\to \mathrm{Ca}(\mathrm{OH}{)}_2+\mathrm{Heat}}$

​Regards,