The orientation probability factor (p) is the fraction of collisions in which the molecules are oriented favourably enough for reaction to occur; its value is less than one. Even when colliding molecules have enough energy, they react only if they meet in the right way. The factor p is one of the contributions to the frequency factor in the Arrhenius equation.

取向概率因子(p)是分子取向足够有利、能够发生反应的碰撞所占的分数;其值小于一。即使碰撞的分子具有足够的能量,也只有当它们以正确的方式相遇时才发生反应。因子 p 是阿伦尼乌斯方程中频率因子的贡献之一。