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# Can i still use Arrhenius Equation -activation enthalpy Watch

1. so i measurd the degradation of ascrobic acid at 4 degrees refrigaration ad 21 degrees room temp kept constant with a a heater for a fortnight, i want to work out the activation energy ,does it still count even though the temperatures are not high. I intent to plot the lnks vs1/t to find the gradient which will be -Ea/R value i think
pls someone help!
2. (Original post by C.JTop)
so i measurd the degradation of ascrobic acid at 4 degrees refrigaration ad 21 degrees room temp kept constant with a a heater for a fortnight, i want to work out the activation energy ,does it still count even though the temperatures are not high. I intent to plot the lnks vs1/t to find the gradient which will be -Ea/R value i think
pls someone help!
ok, think about this; you have got two data which shall give you two point which you can convert using the arrhenius equation into a straight line plot (you are bound to get a straight line connecting only two points)

my point is that your data would be more believable if you have a value at another temperature, be it higher or lower or in between. now, three or more points do not necessarily make a straight line, you might have to draw a best fit line - this is like averaging to reduce your random errors
3. Whether that graph will give the desired results depends on whether or not your reaction is first-order (if so, it will; if not, it won't). However, the Arrhenius equation will always 'work' (to give an estimate) regardless of temperatures, unless you're very close to absolute zero in which case much of normal chemistry (and some of physics) I suspect would fail.
Whether that graph will give the desired results depends on whether or not your reaction is first-order (if so, it will; if not, it won't). However, the Arrhenius equation will always 'work' (to give an estimate) regardless of temperatures, unless you're very close to absolute zero in which case much of normal chemistry (and some of physics) I suspect would fail.
my reaction is first order, thank you.
5. (Original post by shengoc)
ok, think about this; you have got two data which shall give you two point which you can convert using the arrhenius equation into a straight line plot (you are bound to get a straight line connecting only two points)

my point is that your data would be more believable if you have a value at another temperature, be it higher or lower or in between. now, three or more points do not necessarily make a straight line, you might have to draw a best fit line - this is like averaging to reduce your random errors
yeah i know what you mean, but it was kind of impossible to keep a water bath at another temperature for fortnight in my school lab. I'm going to mention about the inaccuracies in my evaluation. thanks

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Updated: April 22, 2013
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