standard reaction

Question

The rate of a standard reaction is 0.01840 M/s at 25° C. It is determined that this is too fast, and that the rate should be reduced to 0.0046 M/s.  What temperature should the reaction be run at to achieve this?

Answer 1

The rule of thumb is a doubling of reaction rate for every 10ºC increase in temperature, or vice versa.  0.0046 is 1/4 of 0.01840, therefore the rule of thumb would indicate a 20ºC decrease in temperature to 5ºC.  You can get a much better estimate if you knew the activation energy in which case you could use the Arrhenius equation to find the new temperature.