WHAT AFFECTS THE RATE OF REACTION
HOW DO WE KNOW WHEN A CHEMICAL REACTION IS OCCURING!
When scientists perform Chemical experiments, sometimes instead of looking at the finished product, they pay attention to another important feature of the experiment. This feature is called the RATE OF REACTION!
The rate of reaction may sound difficult at first, but it really is easy once you’re familiar with what it means! The rate of a reaction is simply how fast or slow a chemical reaction occurs. For example!
Here are two chemical reactions! Baking a Chocolate cake and watching an old car rust away!
PS. you may be wondering “how is making a cake a chemical reaction??”
Watch this short video made by Crash Course Kids to explore how baking a cake can be a chemical reaction!!
Now, these two chemical reactions are very different, not just because one is a cake and one is a car BUT their rate of reaction is specifically different.
Obviously it takes longer for a car to rust than to bake a cake but why? Well, scientists, (as smart as they are) have discovered yet another way to make science more interesting. This discovery is called the COLLISION THEORY!
Now we have two different terms, Rate of reaction and Collision theory! How do these two things relate to a chemical reaction you ask? Well you’re about to find out!
In simple terms, when a chemical reaction happens, the two or more different reactants in the reaction all have their own particles. For a chemical reaction to happen all the particles from each reactant have to collide ( SMASH INTO ) each other to create a large amount of energy to create the new product. Phew! That was a lot to take in! But let’s try to visualize that with numbers instead...so!
1 + 2 + 3 = 6
However, let's pretend each number is a chemical! And each chemical has its own particles.
Number 1 has 1 particle that looks like this: â§
Number 2 has 2 particles that look like this: ⧬⧬
And number 3 has 3 particles that look like that: ⧪⧪⧪
Now! When Chemicals 1, 2 and 3 combine to make the special chemical 6, all their particles will collide to make a lot of energy and become number 6! BUT there’s a problem…
Not all the particles manage to hit each other. Sometimes the particles miss each other and this causes the reaction to take longer! So scientists try to find ways to make sure more particles collide so that the experiment happens faster! WHAT YOU’VE JUST LEARNT IS THE COLLISION THEORY.
COLLISION THEORY!
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The Collision Theory is an idea that the more collisions of particles in a reaction, the faster a chemical reaction will happen!
Scientists have found ways to make more particles collide and make chemical reactions happen faster or slower. These factors include;
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The temperature (how hot or cold the reaction is)
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Concentration (how many particles there are in the chemical reaction)
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Agitation (how much you mix the reaction)
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Surface Area (how much space on a reactant is exposed during the reaction)
Here are a few examples of each:
Temperature
An example of temperature affecting how fast a reaction happens is cooking! If you or your parents are cooking you may turn the heat up on the stove. This is so that the food cooks faster! The heat from the fire gives the particles in the food more energy! And this makes the particles collide more often! Just like in the collision theory!!
Concentration
Concentration means how many particles are in the reaction. For example if you put 1 teaspoon of sugar in your hot chocolate, it wouldn’t be very sweet would it? BUT let’s say you put TEN spoon of sugar in your hot chocolate! It would be much much sweeter, and much more of a reason to visit the dentist! When you add more sugar into the hot chocolate the concentration of sugar in the drink becomes higher!
Agitation
Agitation is just a fancy word for mixing! A simple example is when you mix your hot chocolate so that the milk and water mix well. If you didn’t mix it, the milk and water would probably take a longer amount of time to join together and your drink would go cold. We can use agitation to speed up the rate of reaction when need be.
And finally Surface Area.
Surface area means how much of a reactant is exposed to the reaction. For example, when your mum or dad cooks a potato or a carrot, they usually chop it up first right? Yeah! This is because by chopping them up, when they cook the vegetables they can cook the inside and outside at the same time. This may be hard to visualise in your head so we’ve taken the time to explain this more in our video which you can check on our website!