Moderate

The value of K.E is changed by change in temperature because:

Correct answer: D. Equilibrium position shift without any substance being added or removed.

  • A. Reactants become more reactive than products
  • B. The rate of reaction is increased
  • C. The activation energy of reaction is decreased.
  • D. Equilibrium position shift without any substance being added or removed.

Explanation

Changes in temperature can indeed influence the equilibrium position without any substance being added or removed from the system. When the temperature is altered for a chemical reaction at equilibrium, the equilibrium constant (Kₑ) remains constant, but the position of the equilibrium may shift towards the reactants or products. Le Chatelier's principle explains how changes in temperature affect the position of the equilibrium. It states that when a system at equilibrium is subjected to a change in temperature, pressure, or concentration, the equilibrium will shift to counteract the change and re-establish equilibrium. Endothermic Reaction (Heat as a Reactant): For an endothermic reaction, where heat is a reactant (i.e., the forward reaction absorbs heat), increasing the temperature will favor the forward reaction to absorb the excess heat. As a result, the equilibrium will shift in the direction of the products. A + B ⇌ C + heat Increasing temperature → Shifts equilibrium right → More products formed Exothermic Reaction (Heat as a Product): For an exothermic reaction, where heat is a product (i.e., the forward reaction releases heat), increasing the temperature will favor the reverse reaction to remove the excess heat. Consequently, the equilibrium will shift in the direction of the reactants. C + heat ⇌ A + B Increasing temperature → Shifts equilibrium left → More reactants formed In both cases, the equilibrium constant Kₑ remains constant at a given temperature. However, by altering the temperature, the relative concentrations of reactants and products change, leading to a shift in the equilibrium position. This shift occurs without any addition or removal of substances from the system, solely due to the effect of temperature on the reaction's thermodynamics. In summary, changes in temperature can influence the equilibrium position without adding or removing substances from the system. The equilibrium constant (Kₑ) remains unchanged, but the position of the equilibrium may shift towards the reactants or products based on the endothermic or exothermic nature of the reaction.

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About Chemical Equilibrium

Reversible reactions reach dynamic equilibrium when forward and reverse rates become equal, and Le Chatelier's principle predicts the effect of changing concentration, pressure or temperature. The chapter also covers solubility product, the common ion effect, buffer action and the conditions used in Haber's process, with equilibrium shifts distinguished from changes in the equilibrium constant.

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