Where does the activation energy for a chemical reaction typically come from?

1. The activation energy needed to push reactions forward typically comes as heat energy from the surroundings. 2. Heat speeds up the motion of molecules, increasing the frequency and force with which they collide. 3. It also moves atoms and bonds within a molecule slightly, helping them reach the transition state. 4. Once reactants have absorbed enough heat to reach the transition state, the reaction proceeds. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 6 "Metabolism", section 6.2 Potential, Kinetic, Free, and Activation Energy_