The unit of rate constant k in rate law of first order reaction is
Correct answer: A. Sec-1
- A. Sec-1
- B. Mole dm-3 sec -1
- C. Mole -1 dm+3 sec -1
- D. Mole -2 dm+6 sec -1
Explanation
The rate law for a first-order reaction generally takes the form:Rate = kAwhere:Rate is the change in concentration of the reactant A per unit time (usually expressed in mol/L/s).k is the rate constant, which reflects the intrinsic tendency of the reaction to occur under specific conditions.A is the concentration of the reactant A (in mol/L).To arrive at the correct unit for k, we need to consider the dimensions of the other terms in the equation and ensure they cancel out, leaving only units of time for the rate constant.Since:Rate: mol/L/sSubstituting:k = Rate / A = (mol/L/s) / (mol/L) = s⁻¹Therefore, the unit of k for a first-order reaction is seconds⁻¹.
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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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