The rate constant k for a certain reaction is measured at two different temperatures:temperature k392.0°C ×1.71011470.0°C ×2.91011Assuming the rate constant obeys the Arrhenius equation, calculate the activation energy Ea for this reaction.Round your answer to 2 significant digits.
Question
The rate constant k for a certain reaction is measured at two different temperatures:temperature k392.0°C ×1.71011470.0°C ×2.91011Assuming the rate constant obeys the Arrhenius equation, calculate the activation energy Ea for this reaction.Round your answer to 2 significant digits.
Solution
The Arrhenius equation is given by:
k = A * exp(-Ea / R * T)
where: k is the rate constant, A is the pre-exponential factor, Ea is the activation energy, R is the gas constant, and T is the temperature in Kelvin.
Taking the natural logarithm of both sides gives:
ln(k) = ln(A) - Ea / (R * T)
We can rearrange this to:
Ea = -R * T * ln(k) + ln(A)
We have two sets of values for k and T, so we can set up two equations and subtract one from the other to eliminate ln(A):
Ea = -R * T1 * ln(k1) + ln(A) Ea = -R * T2 * ln(k2) + ln(A)
Subtracting these gives:
0 = -R * T1 * ln(k1) + R * T2 * ln(k2)
Rearranging gives:
R * (T1 * ln(k1) - T2 * ln(k2)) = 0
R * (ln(k1) / T1 - ln(k2) / T2) = 0
So:
Ea = -R * (ln(k1) / T1 - ln(k2) / T2)
We can plug in the given values for k1, k2, T1, and T2, and use R = 8.314 J/(mol*K) to find Ea.
Remember to convert the temperatures from Celsius to Kelvin by adding 273.15.
T1 = 392.0°C = 392.0 + 273.15 = 665.15 K T2 = 470.0°C = 470.0 + 273.15 = 743.15 K
k1 = 1.71 * 10^11 k2 = 2.91 * 10^11
So:
Ea = -8.314 * (ln(1.71 * 10^11) / 665.15 - ln(2.91 * 10^11) / 743.15)
Calculate the value to get the activation energy. Round your answer to 2 significant digits.
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