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Approaching Equilibrium

APCHEM-KHSO4Z

Consider the reaction between hydrogen gas and gaseous carbon disulfide, as described by the equation below.

$${ 4H }_{ 2 }(g)+C{ S }_{ 2 }(g)\rightleftharpoons C{ H }_{ 4 }(g)+2{ H }_{ 2 }S(g)$$

A mixture of all four gases was prepared and allowed to come to equilibrium. The table below shows the initial concentrations of all four species and the equilibrium concentration of methane gas, one of the products.

Reactant or Product Initial Concentration (M) Equilibrium Concentration (M)
${ H }_{ 2 }(g)$ 0.50 ?
$C{ S }_{ 2 }(g)$ 0.30 ?
$C{ H }_{ 4 }(g)$ 0.30 0.25
${ H }_{ 2 }S(g)$ 0.40 ?



Based solely on the data presented above, which of the following correctly describes what takes place as the system moves to an equilibrium state?

A

The system shifts to the left; $Q$ must be greater than $K$.

B

The system shifts to the left; $Q$ must be less than $K$.

C

The system shifts to the right; $Q$ must be greater than $K$.

D

The system shifts to the right; $Q$ must be less than $K$.