Question

The unit of rate constant of a zero order reaction is —

• A. \( min^{-1} \)
• B. \( L\ mol^{-1}\ min^{-1} \)
• C. \( mol\ L^{-1}\ min^{-1} \)
• D. Dimensionless

Hint:

For zero order rate equals k, so k has the units of rate, concentration over time.

Answer 1

The Correct Option is C

Step 1: Apply the master formula \( (mol\ L^{-1})^{1-n}(time)^{-1} \) with \(n = 0\) for a zero order reaction.
Step 2: This gives \( (mol\ L^{-1})^{1-0}(min)^{-1} = (mol\ L^{-1})^{1}\,min^{-1} \).
Step 3: The concentration term stays to the first power, so the unit is \( mol\ L^{-1}\ min^{-1} \). Physically, for a zero order reaction rate equals \(k\), so \(k\) carries the units of rate.
Step 4: A common example is a reaction on a saturated catalyst surface, where the rate is constant until the reactant is used up.
\[\boxed{k_{zero\ order}=mol\ L^{-1}\ min^{-1}}\]