For a problem involving the catalysed reaction of methane and steam, the following reaction table was prepared:

Explain the entries in the “Change” and “Equilibrium” rows.

A physical change of a matter is referred to as a change of state. They are reversible alterations that do not entail any changes to the matter's chemical composition. Melting, freezing, sublimation, deposition, condensation, and vaporisation are all examples of state shifts.

The stationary points of the system's total potential energy characterise the equilibrium states of structural and mechanical systems. The principle of stationary potential energy is what this is called.

As the reaction proceeds, the concentration of products increases and the reactant decreases. The change in amount (pressure) of ${\mathrm{CO}}_2$is + x as one mole is formed. The change in pressure of ${\mathrm{H}}_2$is +4x as 4 moles of ${\mathrm{H}}_2$is formed at equilibrium. The reactant pressure of ${\mathrm{CH}}_4$changes by -x as one mole of ${\mathrm{CH}}_4$reacts.

The change in pressure is -2x as two moles of water react to give a product.

The total pressure of reactants and products will be the sum of initial and change. Thus, the pressure of $\mathrm{CH}4=0.30-\mathrm{x}$and ${\mathrm{H}}_2\mathrm{O}=0.40-2\mathrm{x}$.

The pressure of ${\mathrm{CO}}_2=x$and that of role="math" localid="1657775888145" ${\mathrm{H}}_2=4\mathrm{x}$.