1. What is Rate Constant for First Order Irreversible Reaction?

Definition: The rate constant quantifies the speed of a first-order irreversible chemical reaction, where the reaction rate depends linearly on the concentration of one reactant.

Purpose: This calculator helps chemists and chemical engineers determine the reaction rate constant using conversion data and reaction time.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( k \) — Rate constant (1/second)
• \( X_A \) — Reactant conversion (decimal between 0 and 1)
• \( t \) — Reaction time (seconds)

Explanation: The formula derives from the integrated rate law for first-order reactions, using base-10 logarithm for convenience.

3. Importance of Rate Constant Calculation

Details: Knowing the rate constant is essential for reactor design, process optimization, and predicting reaction behavior under different conditions.

4. Using the Calculator

Tips: Enter the reactant conversion as a decimal (e.g., 0.8 for 80%) and the reaction time in seconds. Conversion must be between 0 and 0.99, and time must be positive.

5. Frequently Asked Questions (FAQ)

Q1: Why is the logarithm used in this formula?
A: The logarithm comes from integrating the first-order rate law, converting exponential decay into a linear relationship.

Q2: What does a higher rate constant indicate?
A: A higher k value means the reaction proceeds faster, with more reactant converting to product in the same time.

Q3: Can I use percentage conversion directly?
A: No, you must convert percentage to decimal (e.g., 75% → 0.75) before entering.

Q4: Why is the reaction irreversible?
A: This formula assumes the reaction only proceeds forward. Different equations apply for reversible reactions.

Q5: What are typical units for first-order rate constants?
A: The units are reciprocal time (1/s, 1/min, etc.), with 1/s being the most common in scientific literature.