Enthalpy of Activation Formula:
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Definition: Enthalpy of activation is approximately equal to the activation energy; the conversion of one into the other depends on the molecularity.
Purpose: It helps in understanding the energy requirements for chemical reactions and the formation of activated complexes.
The calculator uses the formula:
Where:
Explanation: The formula accounts for the difference between activation energy and enthalpy of activation based on the change in gas moles during the reaction.
Details: Understanding enthalpy of activation helps in predicting reaction rates, designing chemical processes, and studying reaction mechanisms.
Tips: Enter the activation energy in J/mol, change in moles of gas (can be positive or negative), and temperature in Kelvin. Temperature must be > 0.
Q1: What's the difference between activation energy and enthalpy of activation?
A: For most reactions in solution, they are nearly equal. The difference becomes significant when there's a change in the number of gas molecules.
Q2: What value should I use for Δng?
A: Calculate the difference in stoichiometric coefficients of gas molecules between the activated complex and reactants.
Q3: Why is temperature important in this calculation?
A: The correction term depends on temperature because it relates to the work done by the system against atmospheric pressure.
Q4: What are typical units for these values?
A: All energy values are in J/mol, temperature in Kelvin, and Δng is unitless.
Q5: Can this be used for reactions in solution?
A: Yes, but the correction term is often negligible unless there's significant volume change during activation.