chemistry help Rates aqa a level
Example
A reaction carried out at 25oC has a value of k = 3.3 × 10−3 mol-1 dm3 s
−1
ln A = 17.1
The gas constant R = 8.31 J K−1 mol−1
Calculate a value for the activation energy in kJ mol-1
Using Equation ln k = ln A – EA/(RT)
Rearrange to EA = (ln A - ln k) x RT = (17.1 - - 5.71) x 8.31 x 298
= 56486 J mol-1
= 56.5 kJ mol-1
How is this correct ,where did the 5.71 come from
A reaction carried out at 25oC has a value of k = 3.3 × 10−3 mol-1 dm3 s
−1
ln A = 17.1
The gas constant R = 8.31 J K−1 mol−1
Calculate a value for the activation energy in kJ mol-1
Using Equation ln k = ln A – EA/(RT)
Rearrange to EA = (ln A - ln k) x RT = (17.1 - - 5.71) x 8.31 x 298
= 56486 J mol-1
= 56.5 kJ mol-1
How is this correct ,where did the 5.71 come from
Original post by fa9089
Example
A reaction carried out at 25oC has a value of k = 3.3 × 10−3 mol-1 dm3 s
−1
ln A = 17.1
The gas constant R = 8.31 J K−1 mol−1
Calculate a value for the activation energy in kJ mol-1
Using Equation ln k = ln A – EA/(RT)
Rearrange to EA = (ln A - ln k) x RT = (17.1 - - 5.71) x 8.31 x 298
= 56486 J mol-1
= 56.5 kJ mol-1
How is this correct ,where did the 5.71 come from
A reaction carried out at 25oC has a value of k = 3.3 × 10−3 mol-1 dm3 s
−1
ln A = 17.1
The gas constant R = 8.31 J K−1 mol−1
Calculate a value for the activation energy in kJ mol-1
Using Equation ln k = ln A – EA/(RT)
Rearrange to EA = (ln A - ln k) x RT = (17.1 - - 5.71) x 8.31 x 298
= 56486 J mol-1
= 56.5 kJ mol-1
How is this correct ,where did the 5.71 come from
-5.71 is the natural log of k
Original post by charco
-5.71 is the natural log of k
what does that means?
Original post by fa9089
what does that means?
You only really need to know what a natural log is if you are doing A level maths.
Otherwise, know that it is a mathematical operation that you can find on your calculator and it is the inverse of the exponential function, e^x.
Your calculator should have a ln( ) button and if you type ln(3.3 x 10^-3), the calculator will give an answer of roughly -5.71. This number is what you use in the rearranged equation.
(edited 4 months ago)
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