Question

The time required for 100% completion of a zero order reaction is
[$R$]$_0$ = Initial concentration of reactant, R

• A. $\dfrac{2k}{[R]_0}$
• B. $\dfrac{[R]_0}{2k}$
• C. $\dfrac{[R]_0}{k}$
• D. $[R]_0 \cdot k$

Hint:

For zero order reactions, the time for complete consumption is calculated using: \[ t = \dfrac{[R]_0}{k} \] Always set $[R] = 0$ for full (100%) completion.

Answer 1

The Correct Option is C

Step 1: Use the integrated rate law for zero order reactions
\[ [R] = [R]_0 - kt \] Step 2: For 100% completion, $[R] = 0$
\[ 0 = [R]_0 - kt \Rightarrow kt = [R]_0 \Rightarrow t = \dfrac{[R]_0}{k} \]