Question

Which of the following reactions of hydrogen with non metals represents Haber’s process?
A) $2H_2+O_2\stackrel{heat}{\to }2H_{2}O,\mathrm{\Delta }H=-285.9kJmo{l}^{-1}$
B)$3H_2+N_2\underset{200atm}{\overset{673KFe}{\to }}2N{H}_3,\mathrm{\Delta }H=-92.6kJmo{l}^{-1}$
C)$H_2+C{l}_2\stackrel{h\nu }{\to }2HCl$
D)$2H_2+C\stackrel{{1100}^{0}C}{\to }C{H}_4$

Answer 1

Hint: The answer is dependent upon the production of a single molecule that is gas which is produced under specific conditions of the temperature and pressure. This can lead you to guess the correct answer.

Complete step – by – step solution:
In our lower classes of inorganic chemistry, we have come across various methods for the production of gases and liquids too among which Haber’s process is the well known process.
Now, let us go through what is actually Haber’s process and what is the reaction from which we can guess the answer.
Now, we know that nitrogen is an inert gas and in the Haber’s process involves the usage of the catalysts which is basically iron catalyst which is used along with molybdenum that acts as the promoter.
This means that in the reaction nitrogen is used. This is an exothermic reaction where the enthalpy of the reaction is of course as negative value.
Among the options given above, option A) and B) is an exothermic reaction.
Among these two, the one reaction in which nitrogen is involved is in option B)
And also Haber’s process makes use of specific conditions of temperature and pressure that is present in the second option.
Therefore, Haber’s process is the one in which nitrogen gas is reacted with hydrogen gas under specific temperature and pressure to give ammonia which is a gas and is evolved out in a reaction. Thus, this process is well known for the production of ammonia.

Therefore, the correct option is B) $3H_2+N_2\underset{200atm}{\overset{673KFe}{\to }}2N{H}_3,\mathrm{\Delta }H=-92.6kJmo{l}^{-1}$.

Note: At the temperature lower than 673K reaction, the process is slow and this is the reason for choosing higher temperature for this method and care is to be taken with temperature and pressure because it affects the yield of ammonia.