Question

If fraction 'a' of HI dissociates at equilibrium in the reaction $2HI\leftrightharpoons H_2+I_2$ then starting with 2 moles of Hl, the total number of moles of the reactants and prodcucts at equilibrium is equal to

• A. 1
• B. 1 +a
• C. 2
• D. 2+a

Answer 1

The correct option is C 2

$2HI\left(g\right)\rightleftharpoons H_2\left(g\right)+I_2\left(g\right)$
Initial $2$ $-$ $-$
At eq. $2-2\alpha$ $\alpha$ $\alpha$

total mole of reactant & product at equlibrium
$=2-2\alpha +\alpha +\alpha =2$