endothermic

Examples of endothermic in the following topics:

• Exothermic and Endothermic Processes

  • In thermodynamics, these two types of reactions are classified as exothermic or endothermic, respectively.
  • As such, the change in enthalpy for an endothermic reaction is always positive.
  • In order to melt the ice cube, heat is required, so the process is endothermic.
  • In an endothermic reaction, the products are higher in energy than the reactants.
  • Paul Andersen explains how heat can be absorbed in endothermic or released in exothermic reactions.

• Thermochemical Equations

  • The sign of the $\Delta H$ value indicates whether or not the system is endothermic or exothermic.
  • In an endothermic system, the $\Delta H$ value is positive, so the reaction absorbs heat into the system.
  • Notice that in an endothermic reaction like the one depicted above, we can think of heat as being a reactant, just like A and B.

• Energy Changes in Chemical Reactions

  • Endothermic reactions, on the other hand, absorb heat and/or light from their surroundings.
  • For example, decomposition reactions are usually endothermic.
  • In endothermic reactions, the products have more enthalpy than the reactants.
  • Thus, an endothermic reaction is said to have a positive enthalpy of reaction.
  • Significant heat energy is needed for this reaction to proceed, so the reaction is endothermic.

• Heat of Solution

  • The breaking of bonds within the solute, such as the electrostatic attraction between two ions (endothermic)
  • The breaking of intermolecular attractive forces within the solvent, such as hydrogen bonds (endothermic)
  • If more energy is used in breaking bonds than is released upon solute-solvent bond formation, then the overall process is endothermic, and ∆Hsol is positive.
  • Dissolution of sodium chloride (table salt) in water is endothermic.
  • Dissolution of sodium chloride in water is endothermic.

• Changes in Temperature

  • Reactions with positive enthalpies—those that absorb heat from their surroundings—are known as endothermic.
  • Endothermic reactions, on the other hand, will be shifted towards product formation as heat is removed from the reaction's surrounding environment.

• Le Chatelier's Principle

  • Recall that for an endothermic reaction, heat is absorbed in the reaction, and the value of $\Delta H$ is positive.
  • Thus, for an endothermic reaction, we can picture heat as being a reactant:
  • Conversely, lowering the temperature on an endothermic reaction will shift the equilibrium to the left, since lowering the temperature in this case is equivalent to removing a reactant.
  • Our heat of reaction is positive, so this reaction is endothermic.
  • Since this reaction is endothermic, heat is a reactant.

• Solid to Gas Phase Transition

  • It is an endothermic phase transition that occurs at temperatures and pressures below a substance's triple point (the temperature and pressure at which all three phases coexist) in its phase diagram.
  • The process of sublimation requires additional energy and is therefore an endothermic change.

• Bond Enthalpy

  • The change ($\Delta H$) is positive in endothermic reactions because the products of the reaction have a greater enthalpy than the reactants, and heat is absorbed by the system from its surroundings.
  • In other words, breaking a bond is an endothermic process, while the formation of bonds is exothermic.

• Solutions and Heats of Hydration

  • The first reaction (ionization) is always endothermic; it takes a lot of work to break up an ionic crystal lattice into its component ions.
  • As often happens for a quantity that is the sum of two large terms having opposite signs, the overall dissolution process can be either endothermic or exothermic.
  • An endothermic process, on the other hand, would show Hsolution as positive, and it would be higher in energy than the starting solute/solvent enthalpies.

• Reaction Rates and Kinetics

  • The potential energy of a reacting system changes as the reaction progresses.The overall change may be exothermic ( energy is released ) or endothermic ( energy must be added ), and there is usually an activation energy requirement as well.