Question

For a zero-order reaction P→Q, the concentration of P becomes half of its initial concentration in 30 minutes after starting the reaction.
The concentration of P becomes zero at ____ minutes. (rounded off to the nearest integer)

Answer 1

Correct Answer: 60

For a zero-order reaction, the concentration of reactant P follows the equation:

\( [P] = [P]_0 - kt \)

Where:

• \( [P]_0 \) is the initial concentration of P,
• \( k \) is the rate constant,
• \( t \) is the time.

We are told that the concentration of P becomes half of its initial concentration in 30 minutes. Therefore, we can express this as:

\( \frac{[P]_0}{2} = [P]_0 - k \cdot 30 \)

Solving for k:

\( k = \frac{[P]_0}{60} \)

Now, to find the time when [P] becomes zero:

\( 0 = [P]_0 - k \cdot t \)

Substituting the value of k:

\( 0 = [P]_0 - \frac{[P]_0}{60} \cdot t \)

Solving for t:

\( t = 60 \text{ minutes} \)

Thus, the concentration of P becomes zero at 60 minutes.