What is a Reagent?

A reagent is a compound or mixture added to a system to start or test a chemical reaction. A reagent can be used to determine the presence or absence of a specific chemical substance as certain reactions are triggered by the binding of reagents to the substance or other related substances.

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Reagent Examples

More reagents in organic chemistry are inorganic compounds or small organic molecules. Reagents used in biotechnology include monoclonal and polyclonal antibodies, oligomers, and cell lines. They are frequently used as colour indicators in analytical chemistry. Grignard reagent, Tollens’ reagent, Fehling’s reagent, Millon’s reagent, Collins reagent, and Fenton’s reagent are named reagents. However, not all reagents are named with the word “reagent.” Reagents also include solvents, enzymes, and catalysts.

Reagents can also be limiting. When limiting reagents are consumed completely, the chemical reaction stops. The chemical reaction is dependent on the reagent to continue and stops when there is no more substance. As a result, the limiting reagents determine when a chemical reaction cannot continue.

Read more: What is Limiting Reagent?

Reagent vs Reactant

The term reagent is frequently used instead of reactant. However, the two terms do not have the same meaning. A reactant is a starting material used in a chemical reaction to produce one or more products, whereas a reagent is not always consumed in a reaction.

Reagent vs Catalyst

A catalyst is a substance that can speed up the rate of a specific chemical reaction, whereas a reagent is a substance or mixture used in chemical analysis or other reactions which can either be a catalyst that accelerates the reaction or a reactant that is consumed during the reaction.

Reagent vs Chemical

A reagent is a commonly available or easily made compound or a known mixture of compounds used to treat materials, samples, other compounds, or reactants in a laboratory or, occasionally, an industrial setting, whereas a chemical is any specific chemical element or chemical compound.

What does Reagent Grade mean?

Chemicals may be labelled as “reagent-grade” or “reagent-quality” by suppliers. This means that the substance is pure enough to be used for chemical or physical analysis. Reagent-grade chemicals are typically free of contaminants that interfere with common tests. Reagent-grade water, for example, has low levels of bacteria, sodium and chlorine ions, and silica impurities. Chemicals that are not reagent-grade are referred to as crude, practical, or technical grade. Lower purity chemicals are more cost-effective and useful for the majority of applications.

The American Chemical Society (ACS) and the American Society for Testing and Materials (ASTM) are two organisations that establish the purity levels for a product to be labelled as reagent-grade.

Uses of Reagents

  1. Reagents are commonly used in laboratories for a variety of tests.Collins reagent, for example, is used to convert alcohols to aldehydes and ketones. As a result, oxidising acid-sensitive compounds can be beneficial. Similarly, Fenton’s reagent is used in oxidation. Fenton’s reagent, on the other hand, catalyses the oxidation of contaminants in water and can be used to remove toxic compounds like tetrachloroethylene.
  2. Reagents are often used to indicate the presence of compounds by causing colour changes to indicate presence.The presence of proteins can be detected using Millon’s reagent. Fehling’s reagent, for example, can detect the presence of carbohydrates or ketones and distinguish between the two functional groups. The presence of proteins, as indicated by the presence of tyrosine residues, causes the solution to turn reddish-brown when Millon’s reagent is added.
  3. One of the most common applications of reagents in everyday life is drug testing. While most kits, such as those used to test for common drugs, are simple to use and involve observing whether a colour change occurs, other kits are more complex and require laboratory equipment, such as chromatography.

Frequently Asked Questions on Reagents


Where are reagents used?

A reagent is an essential component of any chemical reaction. A reagent is a substance or compound that can facilitate a reaction and is used in the majority of commonly used tests. Pregnancy tests, blood glucose tests, and the majority of COVID-19 test kits fall into this category.


What are reagents used in chemical reactions?

Reagents are used to confirm the detection of the presence of another substance.


How do reagents work?

Chemical reactions are triggered by reagents. This term includes organic substances that trigger naturally occurring chains of reactions in the body, as well as inorganic substances that can be used in artificially triggered reactions.


Can reagents be limiting?

Yes, regents can also be limiting. When limiting reagents are consumed completely, the chemical reaction stops. The chemical reaction is dependent on the reagent to continue and stops when there is no more substance.


What is reagent purity?

Reagent grade chemicals are (96-98) % pure, nearly as pure as ACS grade. They are used in the production of food and medicines, as well as in a variety of high-purity laboratory and analytical applications.


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