The units of the rate constant k for a first order reaction are
- A. mol dm-3 s-1
- B. s-1
- C. mol-1 dm3 s-1
- D. mol-2 dm6 s-1
Explanation
For a first order reaction rate equals k times concentration, so k must have units of rate divided by concentration, which reduces to reciprocal seconds. The units of k therefore change with the order, being mol dm-3 s-1 for zero order and mol-1 dm3 s-1 for second order. Checking the units is a quick way to confirm that an order has been deduced correctly.