Chemistry Tuition Singapore

What is a catalyst?

Your chemistry tuition is back with another interesting story as always. Do you know about catalysts? Your chemistry tuition will give you some interesting information on catalysts. A catalyst can be regarded as a material that can alter a chemical reaction rate, merely by its presence and without undergoing any change itself. This process is known as catalysis.
Catalysts are of several types, but are mainly classified in two categories: positive and negative. The positive catalysts are those substances that increase the speed of a chemical reaction while the negative catalysts retard it. For example, when potassium chlorinate is heated to about 400oC, oxygen is evolved but when the manganese dioxide is added to it oxygen is evolved only at 200oC. Manganese dioxide acts as a positive catalyst in this reaction. On the other hand, Gypsum which is added to Portland cement to slow down the hardening process acts as a negative catalyst. In some chemical reaction, the product itself acts as a catalyst. This is called auto catalysis. For example, the decolonization of potassium termagant solution by oxalic acid is very slow in the beginning, but once it starts, it becomes very fast. This is due to the fact that Mn2+ ions act as auto catalyst.
If the catalyst and the reactants are present in the same phase, then the catalysis are called homogeneous catalysis. But if they belong to different phases, then it is known as heterogeneous catalysis.

So how does a chemical substance increases the rate of a reaction simply by its presence?

Catalysts may work in two ways. Surface or contact catalysts work by adsorption. The reacting chemicals are adsorbed to form a concentrated layer at the surface of the catalyst. Due to this the chemicals react more quickly. For example, hydrogen and oxygen combine at the surface of powdered platinum to make water.
According to another theory, a catalyst forms an unstable intermediate compound with one of the reactants. This compound reacts with other reactants more quickly forming the final product. At the end, the catalyst is recovered in the original state by different chemical methods.
Catalysis is very important for the production of plastics, rubber, gasoline, oils, fats, sulfuric acid and ammonia. Catalytic reactions also occur in our body. Enzymes act as catalyst to enhance the digestion process. Enzymes also increase the rate of various processes in the cells of plants and animals. We hope you enjoyed this lesson from chemistry tuition. We will be back with more such interesting findings in our next chemistry tuition.

Best Chemistry Tuition in Singapore

Miracle Learning Centre Pte Ltd specialises in Science and Mathematics. Other than Chemistry, Physics is another Science subject that Miracle is strong in. Chemistry concepts are not easy to explain and not all teachers can explain well. Chemistry concepts are not easy to explain and not all teachers can explain well. All our Chemistry teachers are NIE trained, ex-school teachers who explain concepts very clearly and are able to give examples to elaborate the Physics concept. Chemistry teachers need to be very well versed in the subject to be able to explain the subtle differences in the topic. They will also highlight what to take note of and to be precise in your answers and calculations.