Arrhenius equation
Definition
The Arrhenius equation describes the temperature dependence of reaction rates. It shows how the rate constant $k$ increases exponentially with an increase in temperature.
5 Must Know Facts For Your Next Test
- The formula for the Arrhenius equation is $k = A e^{-E_a/(RT)}$, where $k$ is the rate constant, $A$ is the pre-exponential factor, $E_a$ is the activation energy, $R$ is the gas constant, and $T$ is the temperature in Kelvin.
- A higher activation energy ($E_a$) means that fewer molecules have enough energy to react at a given temperature.
- The pre-exponential factor (A) represents the frequency of collisions with proper orientation for reaction.
- The Arrhenius equation can be rearranged to $\ln(k) = \ln(A) - \frac{E_a}{R} \cdot \frac{1}{T}$ for easier plotting and calculation of $E_a$ from experimental data.
- An important concept related to this equation is that even a small increase in temperature can significantly increase the reaction rate.
Review Questions
- What does each term in the Arrhenius equation represent?
- How does an increase in temperature affect the rate constant according to the Arrhenius equation?
- What information can you derive from a plot of $\ln(k)$ versus $\frac{1}{T}$?
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Related terms
Activation Energy: The minimum amount of energy required for reactants to undergo a chemical reaction.
Rate Constant: A proportionality constant in the rate law that provides a measure of how quickly a reaction occurs.
Pre-exponential Factor: Also known as frequency factor, it represents how often molecules collide with correct orientation per unit time.
