The slowest step, is the one that has the highest activation energy.

慢的步骤是具有高活能的步骤。

This is known as the activation energy.

这被称为活能。

Often though it's just that the reverse reaction has such a high activation energy that the collisions are almost always ineffective.

通常，只是反反应具有如此高的活能，以至于碰撞几乎总是无效的。

A catalyst is a chemical that lowers the activation energy of a reaction, thereby speeding it up without actually being changed by it.

催剂是一种质，可以降低反应的活能，从而在不实际改变的情况下加速反应。

That the slowest step determines the overall rate of the reaction and that the reason for that come right back around the activation energy.

慢的步骤决定了反应的总速率，而其原因又回到了活能附近。