Reaction Rates Activation Energy Chemistry with Educator com

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Reaction Rates Activation Energy Chemistry with Educator com

Educator.com · ⏱ 4:17 · 11.2K مشاهدة · 16 years ago

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the uranous equation gives us relationship between activation energy and rate constants and in this case we have the rate constant at 304 divided by the rate constant at 293 is exactly 2.0 exactly two now from the arous equation remember the ous equation is time pre-exponential factor to the activation energy over RT if we plug in K1 and K2 and simplify it the logarithmic form we get that the logarithm the natural logarithm of K2 temperature 2 over K1 equals the negative of the activation energy over * 1 / T2 - 1 / T1 well let's plug in the data from this problem the logarithm of 2 K2 over K1 and we want to calculate EA has to be expressed in energy units 8.314 JS per per mole T2 is 304 and T1 is one can simplify this somewhat when you have the difference between two small numbers and you want to use your calculator it's usually better to express it by simplifying the algebra 293 minus 304 divided by 293 * 304 carrying through that calculation EA then becomes 4.67 * 10^ 4th JS per mole or 46.7 KJS per mole 46.7 KJ per mole there's an old rule of thumb in chemistry that says if you raise the temperature of reaction by about 10° around room temperature its rate will about double this is an illustration of that you notice we've raised the temperature by 11 about 10° and we see that the activation energy of such reaction if it exactly doubles in rate is about 50 KJS per mole it's just rule of thumb it's handy sometimes useful and expresses fairly familiar and fairly common rate of reaction change and fairly common range for an activation energy