Rate Constant for Backward Reaction Calculator

Formula Used:

\[ k'_{br} = \frac{k_f \times (A_0 - x_{eq})}{x_{eq}^2} \]

Forward Reaction Rate Constant (k_f):

1/s

Initial Concentration of Reactant A (A₀):

mol/m³

Concentration of Reactant at Equilibrium (x_eq):

mol/m³

Rate Constant of Backward Reaction (k'_br): m³/mol·s

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1. What is Rate Constant for Backward Reaction?

Definition: This calculator determines the rate constant for a backward reaction in a second-order chemical equilibrium system.

Purpose: It helps chemists and chemical engineers calculate the backward reaction rate constant when the forward rate constant and equilibrium concentrations are known.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ k'_{br} = \frac{k_f \times (A_0 - x_{eq})}{x_{eq}^2} \]

Where:

\( k'_{br} \) — Rate constant of backward reaction (m³/mol·s)
\( k_f \) — Forward reaction rate constant (1/s)
\( A_0 \) — Initial concentration of reactant A (mol/m³)
\( x_{eq} \) — Concentration of reactant at equilibrium (mol/m³)

Explanation: The formula relates the backward rate constant to the forward rate constant and the equilibrium concentrations of reactants.

3. Importance of Backward Reaction Rate Constant

Details: Knowing both forward and backward rate constants is essential for understanding reaction kinetics, designing chemical reactors, and predicting equilibrium conditions.

4. Using the Calculator

Tips: Enter the forward rate constant, initial concentration of reactant A, and equilibrium concentration of reactant. All values must be positive and the equilibrium concentration must be less than the initial concentration.

5. Frequently Asked Questions (FAQ)

Q1: What units should I use for inputs?
A: Use 1/s for forward rate constant, and mol/m³ for concentrations. The calculator will output m³/mol·s for the backward rate constant.

Q2: Why must x_eq be less than A₀?
A: At equilibrium, some reactant must have been consumed, so the equilibrium concentration must be less than the initial concentration.

Q3: Can this be used for first-order reactions?
A: No, this formula is specific for second-order backward reactions.

Q4: How do I determine the equilibrium concentration?
A: This can be measured experimentally or calculated if the equilibrium constant is known.

Q5: What if my reaction is not at standard conditions?
A: The calculator assumes standard conditions. For other conditions, additional corrections may be needed.