A change in temperature can significantly affect the position of equilibrium, as predicted by Le Chatelier’s Principle. According to this principle, if a system at equilibrium is subjected to a change in temperature, the system will shift in such a way as to counteract that change.
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For an Exothermic Reaction (one that releases heat): If the temperature is increased, the system will shift to favor the reverse reaction (the endothermic direction) to absorb the added heat and reduce the temperature. This shift results in a decrease in the concentration of products and an increase in the concentration of reactants. Conversely, if the temperature is decreased, the system will shift to favor the forward reaction (exothermic direction), releasing heat and increasing the concentration of products.
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For an Endothermic Reaction (one that absorbs heat): If the temperature is increased, the system will shift to favor the forward reaction (endothermic direction), as the reaction absorbs the added heat, resulting in an increase in the concentration of products. If the temperature is decreased, the system will shift to favor the reverse reaction (exothermic direction) to release heat, leading to an increase in the concentration of reactants.
In both cases, temperature changes alter the equilibrium composition. The magnitude of the temperature shift’s effect depends on the enthalpy change (ΔH) of the reaction, which indicates whether the reaction is endothermic or exothermic.