Question

Write the chemical formula for the covalent compound hydrogen iodide and mention its molecular weight in brackets after the formula.

Answer 1

Hydrogen iodide:

• Hydrogen iodide is a covalent compound that is formed by the reaction of hydrogen with iodine.

$\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2}+\underset{\mathrm{Iodine}}{{\mathrm{I}}_2}\to \underset{\mathrm{Hydrogen}\mathrm{iodide}}{2\mathrm{HI}}$

• Hydrogen iodide exists as a colourless gas having molecular formula $\mathbf{HI}$.
• It is used in organic and inorganic synthesis as one of the primary sources of iodine. It is also used as a reducing agent.
• It is composed of one hydrogen atom and one iodine atom.

Molecular weight of Hydrogen iodide = Mass of hydrogen atom + Mass of Iodine atom

Molecular weight of Hydrogen iodide = (1.00 + 126.9) g mol^-1

Thus, the chemical formula and molecular weight of hydrogen iodide is $\mathbf{HI}$ (127.9 g mol^-1).