Question

How can you tell that catalase has been added to hydrogen peroxide?

Answer 1

Catalase is an enzyme that is commonly found in the living beings and results in the decomposition of the hydrogen peroxide when oxygen is present. The addition of catalase in hydrogen peroxide will give water and oxygen.

Complete answer:
Catalase is the enzyme found in almost all the living organisms. It acts as the catalyst for the reaction where the hydrogen peroxide is decomposed in the presence of oxygen gas, this breaking off hydrogen peroxide and results in the formation of two products that is water and oxygen. This enzyme also helps in saving the cells by certain oxidative species that are reactive in nature and thus prevent damage caused due to the process of oxidation. Out of all the enzymes it is found that the highest turnover belongs to the catalase enzyme, it is observed that millions of hydrogen peroxide molecules can be converted into oxygen and water molecules by each catalase enzyme within a single second.
The structure of catalase is quite long as it consists of four long chains of the polypeptide, each chain having around 500 amino acids. It also has an iron or heme group that helps in the breaking of hydrogen peroxide molecules when they react together.
Its reaction can be written as -
$H_2O_ 2 \xrightarrow 2 H_2O+O_2$
This equation indicates that the hydrogen peroxide molecule is broken by the enzyme catalase that results in the formation of water and oxygen. The oxygen evolved is in the form of gas that occurs to be bubbling. The evolution of the oxygen gas occurs quite rapidly but then it dies down after several minutes since the vigor of the enzyme is also decreased due to its loss in kinetic energy. All this reaction simply indicates the decomposition of the peroxide.

Note:
In 1818, the catalase enzyme was the first time noticed by the discoverer of the hydrogen peroxide, named Louis Jacques Thenard. He also stated that some unknown substance is responsible for the breakdown of hydrogen peroxide. The name catalase was first given by Oscar Loew in 1900 and he observed that it is found in several animals and plants.