Question

Which of the following conditions is used to find atomic \[C{{l}_{2}}\] from molecular \[C{{l}_{2}}\]?
(A) High temperature, high pressure
(B) Low temperature, high pressure
(C) High temperature, low pressure
(D) Low temperature, low pressure

Answer 1

Hint: Molecule \[C{{l}_{2}}\] means both chlorine atoms bonded to each other through a covalent bond (both are non-metal) whereas atomic \[C{{l}_{2}}\] means both chlorine atoms are not bonded. For conversion, molecular chlorine to atomic chlorine ∆H should be greater than zero.

Complete Step by Step Answer:
In molecular chlorine, two chlorine atoms are bonded with a covalent bond and a covalent bond are of two types one is polar and the other is non-polar. As there is no electronegativity difference between two chlorine atoms, the bond is nonpolar.

Now to convert molecular chlorine to atomic chlorine this bond must be broken. Thus, we need to give bond dissociation energy due to this, ∆H will be positive or greater than zero. This is the condition of endothermic reaction in which we need to provide a high temperature to break the bond (heat is evolved) such as

High-temperature conditions favour the forward reaction. Other conditions of endothermic reaction of high pressure but high-pressure favour backward reaction. Thus, high pressure is not a good condition for the conversion of molecular chlorine to atomic chlorine. So it will be low pressure which favours the forward reaction (formation of atomic chlorine) such as

Thus, the correct option is C.

Note: At high-pressure reaction proceed to that direction in which less number of moles of gas is present (favour backward reaction) at equilibrium. But as per the given question, we need the condition that favours forward reaction and result in formation of atomic chlorine.