1. What is the Arrhenius Equation for First Order Reactions?

Definition: The Arrhenius equation describes how the rate constant (k) of a chemical reaction depends on temperature and activation energy.

Purpose: This calculator helps chemists and chemical engineers determine reaction rates for first-order reactions at different temperatures.

2. How Does the Calculator Work?

The calculator uses the Arrhenius equation:

Where:

• \( k \) — Rate constant (s⁻¹)
• \( A \) — Frequency factor or pre-exponential factor (s⁻¹)
• \( E_a \) — Activation energy (J/mol)
• \( R \) — Universal gas constant (8.314 J/mol·K)
• \( T \) — Absolute temperature (K)

Explanation: The equation shows that reaction rates increase exponentially with temperature and decrease with higher activation energy.

3. Importance of Rate Constant Calculation

Details: Accurate rate constants are essential for reaction kinetics studies, chemical process design, and predicting reaction behavior under different conditions.

4. Using the Calculator

Tips: Enter the frequency factor (A), activation energy (Eₐ) in J/mol, and temperature in Kelvin. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is the frequency factor (A)?
A: It represents the frequency of collisions with proper orientation for reaction, typically ranging from 10¹⁰ to 10¹⁴ s⁻¹ for first-order reactions.

Q2: How do I determine activation energy?
A: Activation energy can be determined experimentally from the slope of an Arrhenius plot (ln(k) vs 1/T).

Q3: Why must temperature be in Kelvin?
A: The Arrhenius equation requires absolute temperature because it's derived from thermodynamic principles.

Q4: What's a typical range for first-order rate constants?
A: Rate constants vary widely but often fall between 10⁻⁶ to 10⁶ s⁻¹ depending on the reaction and conditions.

Q5: Can I use this for non-first-order reactions?
A: No, this calculator is specifically for first-order reactions. Different forms of the Arrhenius equation exist for other reaction orders.