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Factors Affecting Collision Based Reaction Rates - Concept

Teacher/Instructor Jonathan Fong
Jonathan Fong

M.Ed.,San Francisco State Univ.

Jonathan has been teaching since 2000 and currently teaches chemistry at a top-ranked high school in San Francisco.

Here is some tips, and tricks for factors that affect reaction rates. So reaction rates are basically affected by activation energy. Activation energy is the amount of energy that is required for a reaction to occur. So if we have an energy profile diagram, we basically have energy here on the y axis. Then we have reaction progress, or the amount of time that it happens on the x axis.

Basically, what happens is, if we have a reaction, then these are your reactants, and the amount of energy they have. These are your products, and the amount of energy they have. The amount of energy that it takes to get over that hill, is called the activation energy. So from here to here, that's the activation energy.

Between your reactants and your products, there is a difference. So right here we have this difference is your delta H, or your enthalpy change. It will tell you if a reaction is endothermic, or it's exothermic.

So if you take a look here at the activation energy is a certain amount, and the energy of my reactants is greater than the energy of my products. So that means that energy is being released. So in this particular diagram, we have an exothermic reaction; because energy is being released.

Then so if we take a look here, on our second energy profile diagram, here we have the same amount of activation energy. But what happens is our delta H is now here. So our products have more energy than our reactants. So this is an endothermic reaction, because it's absorbing energy.

Now the important part about reaction rates is the activation energy. How do we lower the activation energy to make the reaction go faster? So there are a couple of things that absorb energy, release energy.

So a couple of things to remember; higher temperatures speed up a reaction. So higher temperatures obviously does make things move faster, so particles move faster just like fire. It makes something have higher temperature. There's more energy, so they move faster. So there are more energy for collisions. So more things will be bouncing off each other and hitting each other. Then you'll have more collisions, and also more opportunities for your reactants to break the bonds.

In the end, to get over the activation energy, your reactants have to break those bonds. Then that's how you end up with a faster reaction. So common sense; at higher temperature, if you increase something then there's more collisions, things move faster.

Also another way you can speed up a reaction is called a catalyst. A catalyst basically speeds up the reaction by finding a different way or a different reaction mechanism. A reaction mechanism is basically another pathway for the reaction to occur. It might be an easier way.

It's just like if you're trying to go home, you might be able to get home by taking the long way home, but it's a faster if you take a more direct route. That's kind of like how a catalyst does it. A catalyst helps you find the direct route. It's like using a GSP rather trying to find your way around without a map, or without a GPS. So you use a different reaction mechanism.

So these ways are the different ways that a reaction can get sped up. So don't forget, factors that affect reaction rates; temperature, speed, amount of collisions. The more collisions you have, the faster it goes. Also the presence of a catalyst. It speeds up a reaction, but does not get used up.

Hopefully, these tips and tricks help you know about the factors of reactions rates, and how to speed up a chemical reaction. Have a good one.