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posted by  DragonCommand15 on 6/29/2008 1:22:25 PM  |  status: Closed  

Activation Energy/ Rate Constant

Course Textbook Chapter Problem
General Chemistry N/A N/A N/A
Question Details:
 
For the gas-phase decomposition of hydrogen iodide:
 
2HI  H2 + I2
 
the rate constant, at 283 degrees C is 3.52 x 10-7 /M-sec. The activation energy for the reaction is 187 kJ/mole. Calculate the rate constant at 293 degrees C.
 
Answer: 7.18 x 10-7 /M-sec.
 
I have probably tried this problem six or seven times, so please show step by step instructions so I can find my error. Thank you so much!
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posted by KyleK on 6/29/2008 2:01:58 PM  |  status: Live
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DragonCommand15's comment:
"Thanks so much! You are awesome!"
Response Details:
Use the Arrhenius equation:
Ea is the activation energy: 187kJ/mol
R is the gas constant: 8.31J/Kmol
T is the temperature
A is the prefactor

First you need to solve for A using the rate constant at 283oC (556K):


Insert this into the equation for 293oC (566K) to find the rate constant at that temp:
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