The Types of catalysts and Touch Surface Area
In solids that react are atoms or molecules on the surface, while atoms or molecules on the inside are closed from the outside, so they cannot react. The number of 'faces' on the outside is called the surface area. The more surface area of the reagent, the greater the chance to react so that the reaction rate will also be faster. (Endang Widjajanti).
Surface Area Touch
The touch surface area affects the reaction rate. The greater the touch surface area, the faster the reaction.
The effect of the touch surface area is related to whether or not the reactant particles meet. If the surface area of the touch increases, the particles more easily meet so that the number of effective collisions will increase, so that the reaction rate also increases.
Catalyst
A catalyst is a substance added to a reaction with the intention of increasing the reaction rate. catalysts are sometimes involved in reactions but do not undergo permanent chemical changes. therefore their presence is usually marked by a notation above the reaction arrow. in other words at the end of the reaction, the catalyst will be found again in the same form and amount as before the reaction. the success or failure of a commercial process to produce a compound often depends on the use of a suitable catalyst. an increase in temperature is one way to increase the fraction of molecules that have energy exceeding the activation energy. Another way that does not require an increase in temperature is to get a reaction path with lower activation energy. (petrucci, 1987)
Catalyst
The role of the catalyst in influencing the reaction rate is related to the reactivation energy, Ea. The catalyst used to accelerate the reaction provides an alternative reaction mechanism with a lower value of Ea compared to the catalyst without reaction Ea. With a lower Ea, more particles have enough kinetic energy to overcome this low Ea obstacle. this causes the number of effective collisions will increase, so the reaction rate will also increase.
The types of catalysts are:
Homogeneous catalyst
Is a catalyst whose form is the same as the form of its reactants.
In chemical reactions, homogeneous catalysts function as intermediaries (facilitators).
Example :
NO2 gas catalyst in the manufacture of SO3 gas.
Cl2 gas catalyst on decomposition N2O
Heterogeneous catalyst
Is a catalyst whose form is different from the shape of the reactants.
The reaction of substances involving this type of catalyst takes place on the surface of the catalyst.
Example :
Ni metal catalyst in the hydrogenation of ethene (C2H4).
Metal catalyst Rodium or Iridium in the process of making ethanoic acid.
Ni metal catalyst in the process of making butter.
Metal catalyst V2O5 in the reaction of making sulfuric acid (Contact process).
Fe metal catalysts in ammonia-making reactions (Haber-Bosch process)
Biocatalyst (enzyme).
Is a catalyst that can accelerate chemical reactions in the body of living things.
The mechanism of action is the "lock and lock" method, popularized by Emil Fischer.
Example :
Amylase enzymes = help hydrolyze starch to maltose.
Catalase = breaks down H2O2 into O2 and H2O
Lipase enzyme = breaks down lipids into glycerol and fatty acids.
AutoCatalyst
Is a reaction substance that functions as a catalyst. That is, the reaction products formed will accelerate chemical reactions.
Example :
The reaction between potassium permanganate (KMnO4) and oxalic acid (H2C2O4) is one of the results of the reaction in the form of manganese sulfate (MnSO4).
The longer, the reaction rate will be faster because the formed MnSO4 serves as a catalyst.
Collision Theory
A substance can react with other substances if the particles collide with each other. The collision that occurs will produce energy to start the reaction. The occurrence of collisions is caused by particles of matter always moving in an irregular direction. Collisions between reacting particles do not always produce reactions. Only collisions that produce enough energy and the right direction of the collision can produce a reaction. Collisions like this are called effective collisions.