alleryStart learning →A rate constant is reported in units of L/mol/s. What is the overall order of its reaction?
AZero order overall
BFirst order overall
CSecond order overall
DThird order overall
Answer & Solution
Correct answer: C. Second order overall
1. The units of k must turn concentration powers into a rate in mol/L/s.
2. For overall order n the units are mol^(1-n) L^(n-1) s^-1.
3. Setting n = 2 gives mol^-1 L s^-1, which is exactly L/mol/s.
4. So a k in L/mol/s belongs to a second order reaction.
5. A first order k carries plain s^-1, since one concentration factor already supplies the mol/L.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 12 "Kinetics", section 12.3 Rate Laws_
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