Question

What is slow and fast reaction? Give example.

Answer 1

Slow and fast reactions:

Slow reactions: There are certain reactions which are extremely slow and might take months to show any measurable change at room temperature. It is also difficult to study the kinetics of such reactions. Some examples are:

• The reaction between hydrogen and oxygen at room temperature.

• The reaction of atmospheric $H_{2}S$ on basic lead acetate.

• The reaction between carbon and oxygen: Carbon and oxygen are thermodynamically less stable than $C{O}_2$ at 298 K, yet coke does not spontaneously catch fire in the air and remains un-reacted even for years.

• The reaction between carbon monoxide and hydrogen: The reaction is thermodynamically feasible at 298 K but in actual practice, the reaction proceeds infinitesimally slowly.

Fast reactions: These reactions are so fast that they occur as soon as the reactants are bought together.

Generally, these reactions involve ionic species and thus, are known as ionic reactions. These reactions take about ${10}^{-14}$ to ${10}^{-16}$ seconds for completion. It is almost impossible to determine the rates of these reactions. Some examples are:

• Precipitation of $AgCl$ when solutions of silver nitrate and sodium chloride are mixed. $AgN{O}_3+NaCl\to AgCl+NaN{O}_3$
• Neutralisation of an acid with a base when their aqueous solutions are mixed. $HCl+NaOH⟶NaCl+H_{2}O$