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does anyone know how to calculate activation energy for a reation? ive looked at all the equations and cant seem to make sense out of them...
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#2
activayion energy, as in to work out the minimum temperature for a reaction to occur, can be worked out by deltaG=deltaH - TdeltaS
rearrange the equation to make T the subject
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rearrange the equation to make T the subject
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#3
come to thing of it im pretty sure if you made deltaH the subject, it'd give you the activation energy in kj/mol
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#4
(Original post by jonesy123)
does anyone know how to calculate activation energy for a reation? ive looked at all the equations and cant seem to make sense out of them...
does anyone know how to calculate activation energy for a reation? ive looked at all the equations and cant seem to make sense out of them...
Then use Arrhenius ...
k = Ae-Ea/RT
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#5
ΔH is not the activation energy, it is enthalpy change in the reaction. Completely different concept.
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okay yes i can rearange that but i cant calculate the rate constant either...god this is annoying -_-
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#8
(Original post by jonesy123)
can i rearrange the rate equation to get the rate constant?
can i rearrange the rate equation to get the rate constant?
... but only after experimentation to obtain the rates at different concentrations and hence the orders of reaction with respect to the reacting components.
Then repeat the process all over again at a different temperature to get a second datum.
(A shortcut would be to assume that the orders don't change at different temperatures)
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yes ive done experiment and found orders of reaction and rates...so i can just plug in numbers and put rate/[concentration]^x and etc? what would the second data set at a different temperature show?
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#10
(Original post by jonesy123)
yes ive done experiment and found orders of reaction and rates...so i can just plug in numbers and put rate/[concentration]^x and etc? what would the second data set at a different temperature show?
yes ive done experiment and found orders of reaction and rates...so i can just plug in numbers and put rate/[concentration]^x and etc? what would the second data set at a different temperature show?
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#11
k = Ae-Ea/RT
Note: you will need experimental data to plot an Arrhenius plot, this will give you the value of activation energy of the given reaction:
K=rate constant
A=exponential factor
ex=quantity(button on calculator)
-Ea=-(activation energy)
R=gas constant (8.31 J K-1 mol-1)
T=temperature (kelvin)
![Image]()
→ we can use this form of the equation to plot lnK against 1/T.
→ This will produce the gradient of -Ea/R:
![Image]()
→ once we have this gradient, we can work out the Ea.
→negative change in y (Δy) over change in x (Δx)
→ (-Δy)/Δx=-Ea, therefore, Ea=(-Ea)x (R (8.31))
You could be asked to do this in an exam, i've seen a few papers where you are asked to do an Arrhenius plot from experimental data, good luck!
Note: you will need experimental data to plot an Arrhenius plot, this will give you the value of activation energy of the given reaction:
K=rate constant
A=exponential factor
ex=quantity(button on calculator)
-Ea=-(activation energy)
R=gas constant (8.31 J K-1 mol-1)
T=temperature (kelvin)
→ we can use this form of the equation to plot lnK against 1/T.
→ This will produce the gradient of -Ea/R:
→ once we have this gradient, we can work out the Ea.
→negative change in y (Δy) over change in x (Δx)
→ (-Δy)/Δx=-Ea, therefore, Ea=(-Ea)x (R (8.31))
You could be asked to do this in an exam, i've seen a few papers where you are asked to do an Arrhenius plot from experimental data, good luck!
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#12
(Original post by Peteyology)
k = Ae-Ea/RT
Note: you will need experimental data to plot an Arrhenius plot, this will give you the value of activation energy of the given reaction:
K=rate constant
A=exponential factor
ex=quantity(button on calculator)
-Ea=-(activation energy)
R=gas constant (8.31 J K-1 mol-1)
T=temperature (kelvin)
![Image]()
→ we can use this form of the equation to plot lnK against 1/T.
→ This will produce the gradient of -Ea/R:
![Image]()
→ once we have this gradient, we can work out the Ea.
→negative change in y (Δy) over change in x (Δx)
→ (-Δy)/Δx=-Ea, therefore, Ea=(-Ea)x (R (8.31))
You could be asked to do this in an exam, i've seen a few papers where you are asked to do an Arrhenius plot from experimental data, good luck!
k = Ae-Ea/RT
Note: you will need experimental data to plot an Arrhenius plot, this will give you the value of activation energy of the given reaction:
K=rate constant
A=exponential factor
ex=quantity(button on calculator)
-Ea=-(activation energy)
R=gas constant (8.31 J K-1 mol-1)
T=temperature (kelvin)
→ we can use this form of the equation to plot lnK against 1/T.
→ This will produce the gradient of -Ea/R:
→ once we have this gradient, we can work out the Ea.
→negative change in y (Δy) over change in x (Δx)
→ (-Δy)/Δx=-Ea, therefore, Ea=(-Ea)x (R (8.31))
You could be asked to do this in an exam, i've seen a few papers where you are asked to do an Arrhenius plot from experimental data, good luck!
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