Question

The unit of rate constant for the zero-order reaction is:
A.)$s^{-1}$
B.)${molL}^{-1}{s}^{-1}$
C.)${Lmol}^{-1}{s}^{-1}$
D.)${L^{2}mol}^{-2}{s}^{-1}$

Answer 1

Hint: The zero-order reaction can be defined as the rate of the reaction is proportional to the zero power of the concentration of reactants [R]. This means the rate is independent of the concentration of the reactant.

Complete answer:
For a zero-order reaction:
$Rate=\frac{dC}{dt}=k{\left[R_0\right]}^{\circ }$
$k=\frac{dC}{dt}=\frac{concentration}{time}$
$k=\frac{mol{L}^{-1}}{s}$
k =$mol{L}^{-1}{s}^{-1}$

So, the correct answer is “Option B”.

Additional Information:
a.)The rate constant is equal to the rate of reaction when the concentration of all the reactants is taken as unity.
b.)The rate constant is nearly doubled with a rise in temperature by ${10}^{\circ }$ for a chemical reaction.
c.)Few examples of zero-order reaction are:

The photochemical reaction between hydrogen and chlorine
Decomposition of $N_{2}O$ on a hot platinum surface.
The decomposition of ${NH}_3$ in the presence of molybdenum or tungsten is a zero-order reaction.
Iodination of acetone in the presence of $H^{+}$ ions.

d.)Zero-order reactions generally occur under the heterogeneous system. In such a system, the reactant is adsorbed on the surface of a solid catalyst, where it is converted into a product. The fraction of the surface of the catalyst covered by the reactant is proportional to the concentration of a reactant at low values. However, after a certain concentration limit of the reactant, the reaction rate does not change i.e. rate becomes independent of concentration and the reaction becomes zero order.

Note:
The possibility to make a mistake just a little portion of the reactant particles are in an area or state wherein they can respond, and this division is consistently recharged from the bigger pool.