Moderate

The reaction rate in forwarding direction decreases with the passage of time because:

Correct answer: A. Concentration of reactants decrease

  • A. Concentration of reactants decrease
  • B. Concentration of product decreases
  • C. The order of reaction changes
  • D. Temperature of the system changes

Explanation

The rate of a chemical reaction depends on the concentration of reactants. As the reaction proceeds, the concentration of reactants decreases while the concentration of products increases. This leads to a decrease in the rate of the reaction in the forward direction with time. The rate of the reverse reaction, on the other hand, increases with time as the concentration of products increases. This is known as a reversible reaction and the rates of the forward and reverse reactions become equal at equilibrium.

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About Reaction Kinetics

Reaction kinetics relates reaction rate to concentration, temperature, surface area and catalysts. Questions cover rate laws, reaction order, rate constants, activation energy and the activated complex, including how a catalyst lowers the activation energy without changing the overall energy change or equilibrium position.

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