The Two Most Common Types Of Catalysts

Catalysts are compounds that accelerate the progress of a reaction without being consumed. They have the ability to increase the rate of reaction in a chemical reaction. Potentially, molecules that would once have taken years to interact, can take seconds with the addition of a catalyst. The overall purpose of a catalyst is to ensure that reactions proceed effectively which is why a range of catalysts are commonly used in many elements of society. Common examples of where catalysts are used include; plastics, clean energy, converting energy sources to fuels, digestion and pharmaceuticals (Hamers 2017). An important feature of a catalyst is that whilst it does increase the rate at which the reaction occurs, the catalyst remains chemically unchanged
after the reaction and is not consumed in the process. This occurs by weakening the bonds between the reactants by stretching them. An effective catalyst will increase the reaction rate but will not change the results.

1.2 Types of Catalysts
Whilst all catalysts do the same thing, there are multiple different types, which all work in slightly different ways.
The most two common types of catalysts are heterogeneous and homogeneous. The difference between the two is how the catalysts sits in the solution, to be specific, what phase the catalyst is in. A phase in a solution is the visible boundaries between two components. For example, a solution with a liquid and solid has two phases whilst a liquid solution consisting of multiple chemicals has just one phase. Although similar to the physical state, the number of phases in a solution is far more general. For example, a solution of oil and water has two phases because of the visible, separate layers (Clark
2002).
Figure 1.2.1 Heterogeneous Catalysts
Heterogeneous catalysts have two phases
Homogenous Catalysts
Homogeneous catalysts have one phase -
Enzymatic Catalysts
In biochemical reactions, enzymes are proteins that act as catalysts.

1.2 Catalysts Effect on Equilibrium
Reactions can be sped up by the addition of a catalyst, including reversible reactions involving a final equilibrium state.
Recall that for a reversible reaction, the equilibrium state is one in which the forward and reverse reaction rates are equal. In the presence of a catalyst, both the forward and reverse reaction rates will speed up equally, thereby allowing the system to reach equilibrium faster. However, it is very important to keep in mind that the addition of a catalyst has no effect whatsoever on the final equilibrium position of the reaction. It simply gets it there faster.
Recall that catalysts are compounds that accelerate the progress of a reaction without being consumed. Common examples of catalysts include acid catalysts and enzymes. Catalysts allow reactions to proceed faster through a lower-energy transition state. By lowering the energy of the transition state, which is the rate-limiting step, catalysts reduce the required energy of activation to allow a reaction to proceed and, in the case of a reversible reaction, reach equilibrium more rapidly.
In the presence of a catalyst, the same amounts of reactants and products will be present at equilibrium as there would be in the uncatalyzed reaction. To state this in chemical terms, catalysts affect the kinetics, but not the thermodynamics, of a reaction.
https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/chemical-equilibrium-14/factors-that-affect-chemical-equilibrium-106/the-effect-of-a-catalyst-447-3459/

1.3 Reaction Rate
The rate of a reaction is the speed at which a chemical reaction happens. If a reaction has a low rate, that means the molecules combine at a slower speed than a reaction with a high rate. The rate of reaction is extremely dependent on the type of molecules that are combining. If there are low concentrations of an essential element or compound, the reaction will be slower. In contrast, if there are high concentration of an essential element or compound, the reaction time will increase.

Rate of reaction can also be linked to the collision theory. The collision theory states that as more collisions in a system occur, there will be more combinations of molecules interacting with each other. The more potential combinations result in a higher chance that the reaction will take place. Ultimately, this means an increased rate of reaction time.
There are many factors which affect reaction rate which include: pressure, temperature and concentration.
The rate of a reaction depends on factors such as:
Activation energy
Temperature: if you heat up the raisin to a high enough temperature, it will probably catch on fire and oxidize
These two factors are closely related: increasing the reaction temperature of the reaction increases the kinetic energy of the reactant molecules. This increases the likelihood that they will have enough energy to get over the activation barrier.

1.4 Catalysts and Reaction Rate
In order to increase the rate of reaction, an increased number of successful collisions must occur. This takes place when more energy in the reaction. Catalysts increase the rate of reaction without being chemically consumed. They do this by lowering the activation energy required for the reaction to take place. With a catalyst, more collisions result in a reaction, so the rate of reaction increases.