# Question Video: Recalling the Practical Changes That Can Be Made to Change the Rate of a Reaction Chemistry • 7th Grade

Which of the following would not increase the rate of a reaction, according to collision theory? [A] Increasing the pressure [B] Increasing the temperature [C] Increasing the surface area of particles [D] Using a catalyst [E] Using a differently shaped container with the same volume

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### Video Transcript

Which of the following would not increase the rate of a reaction according to collision theory? (A) Increasing the pressure, (B) increasing the temperature, (C) increasing the surface area of particles, (D) using a catalyst, or (E) using a differently shaped container with the same volume.

The rate of reaction is the rate at which reactants are converted into the products. Some chemical reactions are explosive and have incredibly fast reaction rates, while others produce products such as rust at a slow rate. Collision theory explains why some chemical reactions happen fast while other happens slow. Collision theory suggests that for a collision to lead to a reaction, the particles must collide with enough energy. These collisions also require the appropriate orientation. This theory also tells us that by increasing the number of collisions, a greater number of successful collisions is more likely and so the rate of reaction increases.

Pressure affects the reaction rate. Highly pressurized particles are close together and collide more frequently. This can lead to an increase in the reaction rate. Since the question asks us which would not increase the rate, we can eliminate answer choice (A).

Temperature also affects the rate of a reaction. Higher temperature particles move faster and collide more often. They also collide with more energy, which increases the likelihood of a successful collision. Increasing the temperature would increase the rate of a reaction, so we can eliminate answer choice (B).

The surface area of the reactants can also affect the frequency of particle collisions. When surface area is increased, the reaction rate can increase as more particle surfaces are available to collide. We can eliminate answer choice (C).

A catalyst lowers the activation energy barrier of a reaction. This means that less energy is required for a successful collision between particles to occur, which can ultimately increase the reaction rate. We can eliminate answer choice (D).

Changing the shape of the container does not significantly affect the particle collision process. If the containers have the same volume of space for the particles to occupy, the container shape should have no effect on how fast the reactants turn into products. Therefore, the container shape would likely not alter the rate of a reaction.

So, the answer choice that would not increase the rate of a reaction, according to collision theory, is answer choice (E): using a differently shaped container with the same volume.