Under what conditions of temperature and pressure, the formation of at...
The formation of atomic hydrogen from molecular hydrogen (H2) can be favored under certain conditions of temperature and pressure. Option 'C' states that high temperature and low pressure favor the formation of atomic hydrogen.
High Temperature:
- At high temperatures, the average kinetic energy of the molecules increases.
- This leads to increased collision energy between the H2 molecules, causing them to break apart more easily.
- The activation energy required for the dissociation of H2 into atomic hydrogen is overcome at high temperatures, promoting the formation of atomic hydrogen.
Low Pressure:
- At low pressures, the number of collisions between H2 molecules decreases.
- This reduces the chances of recombination of the atomic hydrogen formed during dissociation.
- As a result, more atomic hydrogen is retained instead of recombining to form H2.
Explanation:
- The dissociation of molecular hydrogen (H2) into atomic hydrogen (H) is an endothermic process.
- It requires an input of energy to overcome the activation energy barrier and break the covalent bond between the hydrogen atoms.
- At high temperatures, the average kinetic energy of the H2 molecules is high, and more molecules possess the required energy to overcome the activation energy barrier.
- Consequently, the dissociation of H2 into atomic hydrogen is more likely to occur at high temperatures.
- On the other hand, at low pressures, the number of collisions between H2 molecules decreases, reducing the chances of recombination.
- At high pressures, the probability of recombination increases, as there are more collisions between H atoms.
- Therefore, low pressure conditions are favorable for the retention of atomic hydrogen instead of its recombination into H2.
- Hence, the formation of atomic hydrogen from molecular hydrogen is favored most under high temperature and low pressure conditions, as stated in option 'C'.
In summary, high temperatures provide the necessary energy for the dissociation of H2, while low pressures minimize the recombination of atomic hydrogen, leading to a higher concentration of atomic hydrogen.