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What will happen to the molar concentrations of the following molecules if the...

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quinnellow | Student, College Freshman | eNoter

Posted May 20, 2012 at 4:13 PM via web

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What will happen to the molar concentrations of the following molecules if the following variables are adjusted?

Equilibrium equation: XY(g)+heat=X(g)+Y(g)

The initial concentrations are as follows: [XY]=3.0M, [X]=5.0M and [Y]=6.0M

Temperature is decreased

Some X(g) is removed

Some XY(g) is added

Total pressure is increased

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted May 20, 2012 at 4:34 PM (Answer #1)

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The chemical reaction given is: XY(g) + heat <--> X(g) + Y(g). As heat has to be supplied for the compound XY to decompose to X and Y it is an endothermic reaction. The initial amount of XY in the container in which the reaction is taking place is 3 moles. The container has 5 moles of X and 6 moles of Y.

When the temperature is decreased, for an endothermic reaction the value of Keq decreases. This would result in the acceleration of the reverse reaction that is the formation of XY from X and Y. The result would be an increase in the concentration of XY and a decrease in the concentration of X and Y.

If some of X is removed, the equilibrium constant would not change; for a constant Keq if the concentration of the product is decreased, the forward reaction proceeds and this would reduce the concentration of XY while increasing the concentration of Y.

When XY is added, the forward reaction is accelerated, resulting in an increase in the concentration of X and Y.

From the equation it is seen that a molecule of XY is decomposed to one atom of X and one atom of Y. The forward reaction leads to an increase in pressure. If the total pressure of the container is increased the reverse reaction is accelerated leading to a decrease in the concentration of X and Y and an increase in the concentration of XY.

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