Answer:
The rate constant has units of
a) s⁻¹ or /s for a first order reaction.
b) /sM or (s⁻¹M⁻¹) or (L/s.mol) or (L.s⁻¹mol⁻¹) for a second order reaction.
c) /sM² or s⁻¹M⁻² or (L²/s.mol²) or (L².s⁻¹mol⁻²) for a third order reaction.
Explanation:
The rate of a chemical reaction is defined as the amount (in concentration terms) of reactant used up or products formed per unit time. It's units generally is given in the units of concentration per unit time.
Rate = M/s or written extensively as mol/L/s = mol/L.s
And for all types of orders of reactions, the rate of reaction is given as
Rate = kCⁿ
k = Reaction rate constant
C = concentration of specie involved in the reaction
where n is the order of reaction.
Note that the units of the rate of the reaction still has to be mol/L.s or M/s regardless of its order.
M = mol/L
a) For a first order reaction
Rate = kC
M/s = k × M
K = (1/s)
Hence, the rate constant has a unit of /s or s⁻¹
b) Second order reaction
Rate = kC²
M/s = k × M²
k = (1/Ms)
Units of /sM or s⁻¹M⁻¹ or (L/s.mol)
c) Third order reaction
Rate = kC³
M/s = k × M³
k = (1/sM²)
Units of /sM² or s⁻¹M⁻² or (L²/s.mol²)
Hope this Helps!!!
