activation energy

At room temperature( 20 CELSIUS), milk turns sour in about 64 hours. In a refrigerator at 3 celsius, milk can be stored 3 times as long before it sours.

At each temperature, the constant K:       K= c/(souring time) where c is a constant.

1- estimate the activation energy of the reaction that causes the souring of milk

2- HOW LONG WILL IT TAKE MILK TO SOUR AT 40 CELSIUS?