Question

No reaction occurs in which of the following equations?
This question has multiple correct options.
A. ${I^ - } + F{e^{2 + }} \to$
B. ${F_2} + 2NaCl \to$
C. $C{l_2} + 2NaF \to$
D. ${I_2} + 2NaBr \to$

Answer 1

The following reactions may occur if the halogen present in molecular state can replace the halogen present in the compound with sodium. This displacement depends on the value of reduction potential of the halogens. The halogen with a highest reduction potential can displace halogen with less reduction value.

Complete Step by step answer:
The reduction potential is a measure of the tendency of a chemical substance to acquire electrons from or to lose electrons to an electrode. The more positive is the reduction potential, the greater is the substance’s affinity for electrons and tendency to be reduced.

Among halogens, the reduction potential is of the order ${F_2} > C{l_2} > B{r_2} > {I_2}$ i.e., ${F_2}$ (Fluorine) has the highest reduction potential and ${I_2}$ (Iodine) has the least reduction potential. Fluorine has the highest reduction potential due to its small size and the valence shell i.e., the last shell is located close to the nucleus. So, the value of nuclear force is more as compared to the rest of the halogens due to which it has more strength to attract electrons towards it.

So, now we’ll go according to the options.
- In option A, the reaction is not possible as Iodide ion $\left( {{I^ - }} \right)$ has more reduction potential than Iron $\left( {F{e^{2 + }}} \right)$.
- In option B, the reaction is possible as Fluoride ion $\left( {{F^ - }} \right)$ can displace Chloride ion $\left( {C{l^ - }} \right)$ from its compound as fluoride has more reduction potential than Chloride.
- In option C and D, the reactions are not possible as Chloride ion can’t displace Fluoride ion from its compound and similarly Iodide ion $\left( {{I^ - }} \right)$ can’t displace Bromide ion $\left( {B{r^ - }} \right)$ from its compound as Chloride ion has less reduction potential than Fluoride ion and Iodide ion has less reduction potential than Bromide ion.

Therefore, options A, C and D are correct.

Note: Remember the order of reduction potential of halogens as the halogen with more reduction potential can displace another halogen with less reduction potential from its chemical compound.