reactant

Examples of reactant in the following topics:

• Reactants and Reagents

  • Variations in the structure of the reactant may have a marked influence on the course of a reaction, even though the functional group is unchanged.

• Amount of Reactants and Products

  • Stoichiometry is the study of the relative quantities of reactants and products in chemical reactions and how to calculate those quantities.
  • Stoichiometry is the field of chemistry that is concerned with the relative quantities of reactants and products in chemical reactions.
  • For any balanced chemical reaction, whole numbers (coefficients) are used to show the quantities (generally in moles) of both the reactants and products.
  • The relationship between the products and reactants in a balanced chemical equation is very important in understanding the nature of the reaction.
  • A chemical equation shows what reactants are needed to make specific products.

• Predicting the Direction of a Reaction

  • Equilibrium constants can be used to predict whether a reaction will favor the products or the reactants.
  • K is the equilibrium ratio of products to reactants.
  • If K is very large, the reaction will occur mostly to completion, using up almost all the reactants.
  • If the reaction favors the reactants, it will occur in the reverse (right-to-left) direction.
  • If K is very small, the reaction will use up almost all the products and make them into reactants.

• Limiting Reagents

  • This method is most useful when there are only two reactants.
  • One reactant (A) is chosen, and the balanced chemical equation is used to determine the amount of the other reactant (B) necessary to react with A.
  • Then convert the grams of each reactant into moles of NaOH to see how much NaOH each could produce if the other reactant was in excess.
  • STOICHIOMETRY - Limiting Reactant & Excess Reactant Stoichiometry & Moles - YouTube
  • This video also explains how to determine the excess reactant too.

• Introduction to Chemical Reactivity

  • Reactant or Substrate: The organic compound undergoing change in a chemical reaction.
  • The reactant is often (but not always) the larger and more complex molecule in the reacting system.
  • Most (or all) of the reactant molecule is normally incorporated as part of the product molecule.
  • Reagent: A common partner of the reactant in many chemical reactions.
  • Product(s): The final form taken by the major reactant(s) of a reaction.

• Homogeneous Catalysis

  • Homogeneous catalysis is a class of catalysis in which the catalyst occupies the same phase as the reactants.
  • Homogeneous catalysts are those which exist in the same phase (gas or liquid) as the reactants, while heterogeneous catalysts are not in the same phase as the reactants.
  • Most often, homogeneous catalysis involves the introduction of an aqueous phase catalyst into an aqueous solution of reactants.
  • An advantage of homogeneous catalysis is that the catalyst mixes into the reaction mixture, allowing a very high degree of interaction between catalyst and reactant molecules.
  • The model contains reactants which will form the reaction: A₂ + B₂ --> 2 AB.

• Molar Ratios

  • Molar ratios, or conversion factors, identify the number of moles of each reactant needed to form a certain number of moles of each product.
  • The coefficients in a balanced equation can be used as molar ratios, which can act as conversion factors to relate the reactants to the products.
  • These conversion factors state the ratio of reactants that react but do not tell exactly how much of each substance is actually involved in the reaction.
  • The molar ratios identify how many moles of product are formed from a certain amount of reactant, as well as the number of moles of a reactant needed to completely react with a certain amount of another reactant.

• Reaction Stoichiometry

  • Reaction stoichiometry studies the quantitative relationships between reactants and products within a given chemical reaction.
  • In the special case where reactants are combined in their molar ratios (in this case, 1 mole of N2(g) and 3 moles of H2(g)), they will react completely with each other, and no reactant will be left over after the reaction has run to completion.
  • However, in most real-world situations, reactants will not combine in such perfect stoichiometric amounts.
  • This reactant is known as the limiting reactant, or limiting reagent.
  • Stoichiometry can also be used to make useful determinations about limiting reactants, and to calculate the amount of excess reactant(s) left over after a given reaction has run to completion.

• Concentration of Cells

  • Walther Nernst proposed a mathematical model to determine the effect of reactant concentration on the electrochemical cell potential.
  • The standard potential of an electrochemical cell requires standard conditions for all of the reactants.
  • When reactant concentrations differ from standard conditions, the cell potential will deviate from the standard potential.
  • Gibbs' key contribution was to formalize the understanding of the effect of reactant concentration on spontaneity.
  • When a change in the concentration or activity of reactants occurs, or the temperature or pressure changes, the output voltage changes.

• Energy Changes in Chemical Reactions

  • Due to the absorption of energy when chemical bonds are broken, and the release of energy when chemical bonds are formed, chemical reactions almost always involve a change in energy between products and reactants.
  • The energy change in a chemical reaction is due to the difference in the amounts of stored chemical energy between the products and the reactants.
  • In exothermic reactions, the products have less enthalpy than the reactants, and as a result, an exothermic reaction is said to have a negative enthalpy of reaction.
  • This means that the energy required to break the bonds in the reactants is less than the energy released when new bonds form in the products.
  • In endothermic reactions, the products have more enthalpy than the reactants.