Question

what are the unit for rate constants for zero order and second order reaction, if time is expressed in seconds and concentration of reactions in mol/L​

Answer 1

AnswEr :

Consider the following rate equation for an nth order reaction.

$\sf \: r \propto k [A]^n$

Expressing the equation in form of their SI units :

$\implies \sf mol.L {}^{ - 1} {s}^{ - 1} = k \times (mol \: {L}^{ - 1}) {}^{n} \\ \\ \implies \boxed{ \boxed{ \sf \: k_n = (mol {L}^{ - 1} ) {}^{1 - n} {s}^{ - 1} }}$

For a zero order reaction,

$\longrightarrow \sf \: k = (mol.L {}^{ - 1} ) {}^{1 - 0} {s}^{ - 1} \\ \\ \longrightarrow \underline{ \boxed{\sf \: k_0 = mol.L {}^{ - 1} {s}^{ - 1} }}$

For a zero order reaction,the SI unit of the Rate Constant is equal to that of Rate of Reaction.

For a second order reaction,

$\longrightarrow \sf \: k = (mol.L {}^{ - 1} ) {}^{1 - 2} {s}^{ - 1} \\ \\ \longrightarrow \sf k = (mol.L^{-1})^{-1} s^{-1} \\ \\ \longrightarrow \underline{ \boxed{\sf \: k_2 =L mol{}^{ - 1} {s}^{ - 1} }}$

Time taken for the completion of a reaction can be expressed in $\sf min^{-1}$ and $\sf hour^{-1}$ also.

Answer 2

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