Catalyst Regulating Reactions — Overview & Examples

Speeding up Reactions

Catalyst is a broad term used in chemistry to describe any substance that speeds up a chemical reaction and is not destroyed in the process.

Enzymes, a type of common, naturally occurring catalyst, function by lowering the activation energy required to cause a reaction, which increases the reaction rate. As a result, enzyme-catalyzed reactions take much less time to complete than reactions without a catalyst.

Remember the analogy about the hill in your backyard? If it's a really big hill, it will take a long time to walk over. However, if you lower the height of the hill (the activation energy), then you can climb the hill much faster.

If you think of making a soup, you need to turn on the stove top and heat it up. You can let the ingredients sit in the water all day, but without the catalysis of the heat, your soup will stay cold. The enzymes are the flame in this scenario; they cause the reaction to happen much faster. In other words, they are what causes the soup to cook.

Enzymes have a specific location where reactants are brought together to react. These reactants are called substrates and the specific location is called the active site. The shape of the active site is complementary to the specific substrate that it reacts with. This relationship can be thought of as a lock and key. After binding to the active site, the substrates form new compounds called products.

To speed up the rate of reaction, we can increase the temperature to the optimum level, increase the enzyme concentration, or increase the substrate concentration.

If the concentration is high, then the reaction rate will be increased. Concentration means the number of molecules per volume, so a high concentration has a lot of molecules in a specific volume of liquid.

The rate will continue to increase until the enzymes become saturated with substrate. This means that the enzymes are all bound to a substrate and they are working at maximum efficiency. The other alternative, if there are more enzymes than substrates, is that the substrate will run out.

$$\color{#8925AE}{\text{Vocabulary Review:}}$$

$\color{#8925AE}{\text{Enzyme}}$ : A protein made of amino acids that acts like a catalyst. It speeds up biological reactions but is not used up during the reaction

$\color{#8925AE}{\text{Activation Energy}}$ : Minimum amount of energy needed to begin a chemical reaction

$\color{#8925AE}{\text{Catalyst}}$ : A substance that speeds up reactions but is not used up during the reaction

$\color{#8925AE}{\text{Substrate}}$ : Molecules that a specific enzyme binds to and recognizes. They are transformed during the reaction

What Is a Catalyst?

A catalyst is something that can lower the energy requirement for a reaction or make the reaction happen faster. A catalyst is not used up or destroyed by the reaction; it just helps out.

Many biological catalysts are used to bring substrates, or reactants, together. By grabbing the substrates in an active site and pushing them together, an enzyme makes sure that the reaction will occur and create a product. If the substrates had to float around and just hope that they run into each other to react, the reaction might never occur.

(Video) Activation Energy: Kickstarting Chemical Reactions

by Vance Kite on TED-Ed

You may have heard that enzymes help lower activation energy, but how exactly do they do that? This video explains it all by comparing a reaction to a race and showing the teammates that help along the way.