Final answer:
Activation energy is required to start a chemical reaction, serving as the initial 'push' to overcome the energy barrier. The law of mass action states that higher reactant concentrations result in faster reaction rates as it increases the frequency of effective collisions.
Step-by-step explanation:
The 'push' needed to start a chemical reaction is activation energy. Activation energy is the minimum energy necessary for reactants to collide with enough force to break bonds and begin a reaction. It's akin to the push needed for a child to start sliding on a playground slide. Once the activation energy threshold is met, the reaction can proceed.
A higher concentration of molecules does indeed cause a faster chemical reaction. This concept is known as the law of mass action, which predicts that a reaction rate is directly proportional to the concentration of reactants. When more reactant molecules are present, it is more likely they will collide with the correct orientation necessary for the reaction to take place, thus increasing the reaction rate.