Final answer:
An increase in temperature boosts spontaneous chemical reactions by both increasing the frequency and energy of reactant collisions, leading to more successful collisions that overcome the activation energy barrier and form products.
Step-by-step explanation:
An increase in temperature increases the rate at which a spontaneous reaction occurs in a test tube. This is due to two main factors: the increase in the frequency of collisions between reactant particles and the energy of those collisions.
When the temperature of a reaction mixture is increased, the reactant particles move faster, leading to a greater number of collisions. However, more importantly, this increase in temperature also means that the collisions occur with greater energy. This increased energy increases the likelihood that the collisions will have enough energy to surpass the activation energy barrier, thus forming products. As a result, increasing temperature not only increases the frequency of effective collisions but also the percentage of those collisions which are effective, ultimately increasing the reaction rate.
In addition, higher temperatures result in more molecules having energy greater than the activation energy, further contributing to the increased rate of reactions. Other factors that can affect the rate of reactions include concentration and catalysts, but temperature has one of the most significant impacts.