Which statement about reaction rates is true?
Responses
Changing the surface area affects the reaction rate.
Changing the surface area affects the reaction rate.
Changing the amount of reactants will not change the reaction rate.
Changing the amount of reactants will not change the reaction rate.
Changing the temperature cannot speed up a reaction rate.
Changing the temperature cannot speed up a reaction rate.
A catalyst slows down the reaction rate.
Changing the surface area affects the reaction rate.
The correct statement about reaction rates is that changing the surface area affects the reaction rate.
The correct statement about reaction rates is: Changing the surface area affects the reaction rate.
When it comes to reaction rates, the surface area of the reactants plays a crucial role. Increasing the surface area of a substance can result in a faster reaction rate. This is because a greater surface area allows more reactant particles to come into contact with each other, leading to a higher frequency of successful collisions and a faster rate of reaction. On the other hand, decreasing the surface area reduces the number of available contact points, resulting in a slower reaction rate.
To understand why changing the surface area affects the reaction rate, you can conduct an experiment. First, consider a solid reactant, such as a piece of metal. If you leave the metal as a large chunk, only the outer surface area is exposed to the other reactant(s). However, if you were to break the metal into small pieces or powder, the surface area would increase significantly. This increase in surface area allows for more surface-to-surface contact between the reactants, making it easier for them to interact and leading to a faster reaction rate.
By contrast, the other statements are incorrect:
- Changing the amount of reactants can indeed affect the reaction rate. Increasing the concentration or quantity of reactants typically leads to a faster reaction, as there are more reactant particles available to collide with each other.
- Changing the temperature can significantly influence the reaction rate. In general, increasing the temperature increases the energy of the reactant particles, making them move faster and collide more frequently. This increased collision rate enhances the chances of successful collisions, resulting in a faster reaction rate. On the other hand, lowering the temperature reduces the particle energy and slows down the reaction rate.
- A catalyst is a substance that speeds up a reaction rate without being consumed in the reaction itself. It achieves this by providing an alternative reaction pathway with a lower activation energy. In other words, a catalyst allows the reactants to overcome the energy barrier required for the reaction to occur more easily. As a result, a catalyst increases the reaction rate rather than slowing it down.