Final answer:
A chemical reaction's feasibility depends on factors like activation energy, temperature, reactant concentration, and catalyst presence. Activation energy represents a critical threshold that reactants must overcome to react, while temperature and concentration influence kinetic energy and collision frequency respectively. Catalysts facilitate reactions by lowering the activation energy barrier.
Step-by-step explanation:
What determines whether or not a chemical reaction is possible when substances are combined is dependent on several factors. These include the activation energy, the temperature of the reactants, the concentration of reactants, and the presence of a catalyst. Activation energy is crucial as it is the minimum energy that colliding particles must have to undergo a reaction. Temperature can influence the kinetic energy of the reactants, thus affecting their ability to reach the activation energy needed for the reaction to proceed. The concentration of reactants affects the probability of collision, which can also determine the likelihood of a reaction occurring. A catalyst, on the other hand, can lower the activation energy barrier without being consumed in the reaction, therefore facilitating the reaction process.
For instance, when reactant particles are provided with heat energy, their kinetic energy increases, leading to more forceful collisions and a greater chance of overcoming the activation energy barrier, making a chemical bond more likely to break and the reaction to occur. Conversely, low temperatures might not provide enough energy for reactants to reach the activation energy required for a reaction. Catalysts play a role in providing an alternative path with a lower activation energy for the reaction to proceed. These factors are all essential in determining if a chemical reaction is possible when substances are combined.