$$\ce{Li2O + 2KCl <=> 2LiCl + K2O}$$
I got this reaction on a test question paper. With three other options, it was asked whether this reaction is feasible or not?
I googled it and found the reverse reaction of at every webpage I looked. So, it seems to me it isn't feasible.
I think that the reverse reaction is feasible because $\ce{LiCl}$ is quite covalent in nature(Fajan's rule) So, for becoming more ionic in nature $\ce{Li+}$ makes bond with oxygen ion. (I now think it's a bogus reasoning)
What could be the reason behind it? Is it feasible?
Answer
Although every reaction is reversible in nature, let's try to understand where the equilibrium might be biased, i.e. whether the reactant side favoured or the product side.
A rule of thumb while predicting feasibility is to remember, a reaction where you can get a weak acid from a strong acid is feasible.
$$\ce{Strong Acid -> Weak acid}$$
In your case we're dealing with $\ce{KCl}$ and $\ce{LiCl}$. The acidic or basic nature or salts is determined by the extent of hydrolysis of its ions. Ions from a weaker species undergo hydrolysis while ions from a stronger species don't. Another way to look at this is to compare the acidic and basic strengths of the acids and bases which formed them in the first place. $$\ce{LiOH + HCl -> LiCl + H2O}$$ $$\ce{KOH + HCl -> KCl + H2O}$$ Notice that $\ce{HCl}$ is common to both of these species, so we have to just compare the basic strengths of $\ce{LiOH}$ and $\ce{KOH}$. Down the group (in alkali metal hydroxides) basic strength increases. So $\ce{KOH}$ is a better base. And thus $\ce{KCl}$ is a weaker acid. Since we're making a stronger acid from a weaker acid, the reaction can be termed as unfeasible.
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