A 160 lb. college student consumes a bowl of cereal containing 750 Calories in the morning. He then sits quietly in class for 4 hours, and then goes for a 30-minute run. How many Calories did he use, and was it more or less than he consumed?

and after water is usually warmed by the sun the water temperature raises and then evaporates .

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.

its probably to later but whats the question