WJEC Chemistry Practice Exam

When reacting particles in a chemical reaction are used up, the consequence is that there are fewer reacting particles available to collide with each other. This directly impacts the rate of the reaction, as successful collisions between particles are necessary for the reaction to occur. As the concentration of particles decreases, the chances of these successful collisions also decrease, leading to a slowdown in the reaction process.

In this context, the continuous consumption of the reactants means that as time progresses, there will be fewer reactants in the mixture, ultimately resulting in fewer opportunities for those particles to collide and react. This understanding is fundamental to the principles of chemical kinetics, where concentration is a key factor affecting the reaction rate.