Question

Equal volumes of 1 M HCl and 1 M ${{H}_{2}}S{{O}_{4}}$ are neutralized by 1M NaOH solution and x and y kJ equivalent heat are liberated respectively. Which of the following relations is correct.

A. x = 2y

B. x = 3y

C. x = 4y

D. x = 0.5y

Answer 1

Hint : When acid and base react they form a salt and release some amount of energy also. These types of reactions are called exothermic reactions and neutralization reactions due to the formation of a neutral compound (salt). The amount of heat liberated in a reaction depends on the number of protons released during the reaction.
Complete step by step solution :
In the question it is given that 1 M HCL and 1 M ${{H}_{2}}S{{O}_{4}}$reacts with 1 M NaOH solution and liberates x and y kJ equivalents of heat.
HCl dissociates and gives the following products.
$HCl\to {{H}^{+}}+C{{l}^{-}},\text{ }\Delta H=x$
${{H}_{2}}S{{O}_{4}}$ dissociates and gives the following products.
${{H}_{2}}S{{O}_{4}}\to 2{{H}^{+}}+SO_{4}^{2-},\text{ }\Delta H=y$
From the above equations we can say that HCl gives one mole of ${{H}^{+}}$and ${{H}_{2}}S{{O}_{4}}$gives two moles of${{H}^{+}}$, means ${{H}_{2}}S{{O}_{4}}$releases double amount of heat when compared to HCl in neutralization reaction with 1 M NaOH solution.

Therefore, $x=\dfrac{y}{2}\text{or }y=2x\text{ or }x=0.5y$.

So, the correct option is D.

Note : Hydrochloric acid liberates less amount of heat when compared to sulphuric acid during neutralisation reaction because sulphuric acid contains two protons and hydrochloric acid contains only one proton. Coming to sulphuric acid and nitric acid, nitric acid releases more heat compared to sulphuric acid, because nitric acid contains three protons and sulphuric acid contains two protons.