Math Problem Statement

The rate constant reaction is 0.01439 mim*-1 at 298k and its activation energy is 70000 mol *-1. What is the value rate constant at 313k

Solution

To calculate the rate constant at 313 K, we can again use the Arrhenius equation in its comparative form:

ln(k2k1)=EaR(1T21T1)\ln\left(\frac{k_2}{k_1}\right) = -\frac{E_a}{R} \left(\frac{1}{T_2} - \frac{1}{T_1}\right)

Given:

  • k1=0.01439min1k_1 = 0.01439 \, \text{min}^{-1} (rate constant at 298 K),
  • T1=298KT_1 = 298 \, \text{K},
  • T2=313KT_2 = 313 \, \text{K},
  • Ea=70000J/molE_a = 70000 \, \text{J/mol} (activation energy),
  • R=8.314J/mol\cdotpKR = 8.314 \, \text{J/mol·K}.

Step 1: Calculate the term EaR\frac{E_a}{R}

EaR=70000J/mol8.314J/mol\cdotpK=8418.32K\frac{E_a}{R} = \frac{70000 \, \text{J/mol}}{8.314 \, \text{J/mol·K}} = 8418.32 \, \text{K}

Step 2: Calculate 1T21T1\frac{1}{T_2} - \frac{1}{T_1}

1T21T1=1313K1298K=298313298×313K1=1593274K10.0001608K1\frac{1}{T_2} - \frac{1}{T_1} = \frac{1}{313 \, \text{K}} - \frac{1}{298 \, \text{K}} = \frac{298 - 313}{298 \times 313} \, \text{K}^{-1} = -\frac{15}{93274} \, \text{K}^{-1} \approx -0.0001608 \, \text{K}^{-1}

Step 3: Calculate ln(k2k1)\ln\left(\frac{k_2}{k_1}\right)

ln(k2k1)=8418.32K×0.0001608K11.353\ln\left(\frac{k_2}{k_1}\right) = -8418.32 \, \text{K} \times -0.0001608 \, \text{K}^{-1} \approx 1.353

Step 4: Solve for k2k_2

k2k1=e1.3533.869\frac{k_2}{k_1} = e^{1.353} \approx 3.869

k2=k1×3.869=0.01439min1×3.8690.0557min1k_2 = k_1 \times 3.869 = 0.01439 \, \text{min}^{-1} \times 3.869 \approx 0.0557 \, \text{min}^{-1}

So, the rate constant of the reaction at 313 K is approximately 0.0557min10.0557 \, \text{min}^{-1}.

Would you like further details or have any other questions?


Here are some related questions:

  1. How does the activation energy affect the rate constant at different temperatures?
  2. What are some methods to experimentally determine the activation energy of a reaction?
  3. How does the Arrhenius equation apply to non-ideal systems?
  4. What happens to the rate constant if the temperature increases by a larger amount, say to 350 K?
  5. Can the Arrhenius equation be used to predict reaction behavior at very low temperatures?

Tip: Always check the consistency of your units when using the Arrhenius equation, especially when switching between time units like minutes and seconds.

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Math Problem Analysis

Mathematical Concepts

Arrhenius equation
Activation energy
Temperature dependence of rate constants

Formulas

Arrhenius equation: ln(k2/k1) = -Ea/R * (1/T2 - 1/T1)

Theorems

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Suitable Grade Level

Undergraduate level