reactant

(noun)

Any of the participants present at the start of a chemical reaction.

Related Terms

  • molecule
  • reaction

Examples of reactant in the following topics:

  • Chemical Reactions and Molecules

    • An arrow is typically drawn between the reactants and products to indicate the direction of the chemical reaction.
    • The reactant hydrogen peroxide is broken down into water (H2O), and oxygen, which consists of two bonded oxygen atoms (O2).
    • Some chemical reactions, such as the one shown above, can proceed in one direction until the reactants are all used up.
    • In reversible reactions, reactants are turned into products, but when the concentration of product goes beyond a certain threshold, some of these products will be converted back into reactants; at this point, the designations of products and reactants are reversed.
    • In biological reactions, however, equilibrium is rarely obtained because the concentrations of the reactants or products or both are constantly changing, often with a product of one reaction being a reactant for another.
  • Activation Energy

    • For this reason, reactant molecules don't last long in their transition state, but very quickly proceed to the next steps of the chemical reaction.
    • Whether the reaction is exergonic (ΔG<0) or endergonic (ΔG>0) determines whether the products in the diagram will exist at a lower or higher energy state than the reactants.
    • For this reason, heating up a system will cause chemical reactants within that system to react more frequently.
    • Once reactants have absorbed enough heat energy from their surroundings to reach the transition state, the reaction will proceed.
    • In this endergonic reaction, activation energy is still required to transform the reactants A + B into the product C.
  • Enzyme Active Site and Substrate Specificity

    • Enzymes bind with chemical reactants called substrates.
    • In some reactions, a single-reactant substrate is broken down into multiple products.
    • Two reactants might also enter a reaction, both become modified, and leave the reaction as two products.
  • Connecting Proteins to Glucose Metabolism

    • Many of the substrates, intermediates, and products in a particular pathway are reactants in other pathways.
  • Citric Acid Cycle

    • Because the final product of the citric acid cycle is also the first reactant, the cycle runs continuously in the presence of sufficient reactants.
  • ATP in Metabolism

    • In many cellular chemical reactions, enzymes bind to several substrates or reactants to form a temporary intermediate complex that allow the substrates and reactants to more readily react with each other.
  • Free Energy

    • A negative ∆G also means that the products of the reaction have less free energy than the reactants because they gave off some free energy during the reaction.
    • In this case, the products have more free energy than the reactants.
  • Connecting Other Sugars to Glucose Metabolism

    • Many of the substrates, intermediates, and products in a particular pathway are reactants in other pathways.
  • Main Structures and Summary of Photosynthesis

    • In reality, the process includes many steps involving intermediate reactants and products.
  • The Two Parts of Photosynthesis

    • Although the light-independent reactions do not use light as a reactant (and as a result can take place at day or night), they require the products of the light-dependent reactions to function.
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