Question

identify the order of reaction from the given rate constant k is equal to 2.6 into 10 raise to power minus 4 mole inverse 1 and second inverse 1​

Answer 1

The order of the reaction is second order.

• The SI unit of rate constant, k tells about the order of the reaction.
• Order of reaction can be zero, first or second-order reaction.
• k = Rate of the reaction/concentration of the reactants
• The mathematical expression for k in terms of SI unit:

        k  = (concentration / time) x [1 / (concentration)ⁿ ]

        here, n is the order of the reaction that can be 0, 1, 2.

        concentration is expressed in mol/L, and time is expressed in s.

• So, k can be written as:

        k  =  [ (mol/L)  / s) ]  x  [ 1 / (mol/L)ⁿ]

• For example, for second-order reaction:

        n = 2

        ∴ k =  [ (mol/L)  / s) ]  x  [ 1 / (mol/L)² ]

           k =   [ 1 / s) ]  x  [ 1 / (mol / L) ]

           k =   (1 / s) x ( L x 1 / mol)

           k =  L / mol / s

          k = L / mol / s

           k = L mol⁻¹ s⁻¹

• As per question, k = 2.6 x 10⁻⁴ L mol⁻¹ s⁻¹
• Its SI unit is in  L / mol / s, which means the order of the reaction is second order.