The temperature dependence of the rate constant for a reaction is tabulated as follows: Temperature (K) k 1M 1 s1 2 600 0.028 650 0.22 700 1.3 750 6.0 800 23 Calculate Ea and A.

Verified step by step guidance

1. Identify the Arrhenius equation: $k = A e^{-\frac{E_a}{RT}}$, where $k$ is the rate constant, $A$ is the pre-exponential factor, $E_a$ is the activation energy, $R$ is the gas constant (8.314 J/mol·K), and $T$ is the temperature in Kelvin.
2. Take the natural logarithm of both sides of the Arrhenius equation to linearize it: $\ln k = \ln A - \frac{E_a}{R} \cdot \frac{1}{T}$.
3. Plot $\ln k$ versus $\frac{1}{T}$ using the given data points. The slope of the line will be $-\frac{E_a}{R}$, and the y-intercept will be $\ln A$.
4. Calculate the slope of the line from the plot, which is $-\frac{E_a}{R}$. Use this slope to solve for $E_a$ by rearranging the equation: $E_a = -\text{slope} \times R$.
5. Determine the y-intercept from the plot, which is $\ln A$. Solve for $A$ by taking the exponential of the y-intercept: $A = e^{\text{y-intercept}}$.

Key Concepts

Arrhenius Equation

The Arrhenius equation relates the rate constant (k) of a chemical reaction to the temperature (T) and activation energy (Ea). It is expressed as k = A * e^(-Ea/(RT)), where A is the pre-exponential factor, R is the universal gas constant, and T is the temperature in Kelvin. This equation highlights how temperature influences reaction rates and is fundamental for calculating Ea and A.

Activation Energy (Ea)

Activation energy (Ea) is the minimum energy required for a chemical reaction to occur. It represents the energy barrier that reactants must overcome to form products. A higher Ea indicates a slower reaction rate at a given temperature, while a lower Ea suggests a faster reaction. Understanding Ea is crucial for predicting how temperature changes affect reaction rates.

Pre-exponential Factor (A)

The pre-exponential factor (A) in the Arrhenius equation is a constant that represents the frequency of collisions and the orientation of reactants during a reaction. It reflects the likelihood that collisions will lead to a successful reaction. A is temperature-dependent and can be determined alongside Ea when analyzing the temperature dependence of rate constants.