Question

Equations of two chemical reactions are given :
$h_2+{Cl}_2\to 2HCl$
$Ca{CO}_3+2HCl\to Ca{Cl}_2+{CO}_2+H_{2}O$
Explain the reason for the following situations using collision theory.
(a) When pressure decreases, the speed of formation of $HCl$ decreases.
(b) When the particle size of $Ca{CO}_3$ decreases speed of chemical reaction increases.
(c) All collisions between reactant molecules are not leading to a chemical reaction.

Answer 1

(a) When pressure is decreased, the number of collisions between reactant particles also decreases resulting in a slow rate of formation of $HCl$.
(b)When the particle size of $Ca{CO}_3$ decreases, the rate of collision of particles increases because of which the speed of chemical reaction increases.
(c) Only those molecules having energy greater than a certain threshold value can undergo effective collisions leading to the formation of products.