$4$ Gaseous hydrogen and gaseous lodine react together to form hydrogen lodide.

Totelf :

$H_2+r_2=2HI$

The graph shows how the amount of hydrogen iodide varies with time in a $1\mathrm{.}00d{m}^3$ container.

The initial amounts of hydrogen and lodine were $1\mathrm{.}00mol{H}_2$ and $1\mathrm{.}00mol{l}_2.$

Sketch a similar graph to show how the number of moles of hydrogen varies with time.

$[5]$

b Calculate the number of moles of lodine present at equilibrium.

$111.$

c I Write the equilibrium expression for $K_c$ for the reaction between gaseous hydrogen and iodine.

$[1]$

if Calculate the value of $K_c$ and give the units.

$[2]$