Provide an example of the half-life of different reactions.

The half-life of a reaction is the time taken for half of the reactants to be used up.

Different reactions have different half-lives depending on their rate of reaction. For example, the half-life of radioactive decay can range from fractions of a second to billions of years. Carbon-14, a radioactive isotope used in dating archaeological artifacts, has a half-life of 5,700 years. This means that after 5,700 years, half of the original amount of carbon-14 will have decayed into nitrogen-14.

Enzyme-catalysed reactions also have half-lives. The half-life of an enzyme-catalysed reaction depends on the concentration of the enzyme and substrate, as well as the temperature and pH of the reaction. For example, the half-life of the enzyme catalase in breaking down hydrogen peroxide can range from a few seconds to several minutes depending on these factors.

Chemical reactions also have half-lives. The half-life of a chemical reaction depends on the concentration of the reactants, the temperature, and the presence of a catalyst. For example, the half-life of the reaction between hydrogen and iodine to form hydrogen iodide can range from a few seconds to several minutes depending on these factors.

Understanding the half-life of different reactions is important in fields such as medicine, where the half-life of drugs can determine their effectiveness and dosage. It is also important in nuclear physics, where the half-life of radioactive isotopes is used to determine their decay rate and potential hazards.