When heated, a non-radioactive halogen, x, reversibly reacts with hydrogen to form HX. identify x and explain the reversibility of the reaction

X is Iodine

Explanation:

The halogens react with hydrogen to produce compounds called hydrogen halides.

The hydrogen halides are gases at room temperature. They dissolve in water to produce acidic solutions.

The different observations seen when halogens react with hydrogen is given below;

Fluorine: Explodes in the cold and dark, forming hydrogen fluoride

Chlorine: Explodes with a flame or in sunlight, forming hydrogen chloride

Bromine: Vigorous reaction with burning hydrogen, forming hydrogen bromide

Iodine: Very slow reaction when heated strongly, forming some hydrogen iodide.

From the above observations, it can be seen that iodine reacts least vigorously with hydrogen and requires heating for the reaction to proceed to product formation.

A reaction is said to be reversible if both the reactants and products are in equilibrium with each other. The equilibrium constant K also depends upon the Gibbs enthalpy (G) of the reaction. If change in G is negative, the reaction is feasible. However, the reaction between iodine and hydrogen is endothermic (G is positive). Heat is supplied to favor the forward reaction and the reaction becomes reversible once heat is removed.