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Negative. Heat is lost.

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โˆ™ 2012-03-10 20:59:45
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Q: Is the change in enthalpy positive or negative for an exothermic reaction?
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Related questions

How do you know if an enthalpy is negative or positive?

The enthalpy is negative if the process emits heat. Therefore if the DeltaHrxn is negative, the reaction is exothermic.

What is known about a reaction with a negative enthalpy?

The reaction is exothermic

Is polymerization endothermic or exothermic?

Exothermic, because the reaction enthalpy must be negative. With polymerization, the entropy decreases. The Gibbs energy has to be negative. Thus negative reaction enthalpy. Gibbs energy = reaction enthalpy - temperature*entropy

Is the reaction between hydrochloric acid and sodium hydroxide endothermic or exothermic?

Exothermic, the enthalpy is negative for the reaction.

Is vaporisation an exothermic or endothermic process?

Any reaction categories into exothermic and endothermic based upon change in enthalpy of reaction. If difference in enthalpy of product and reactant comes positive value then it is termed as endothermic and if it is negative value then exothermic reaction. Usually, vaporisation is considered as exothermic due to release in energy.

Are titrations endothermic or exothermic?

In thermometric titration the reaction enthalpy is used to follow the chemical reaction. I guess it dépends on the titration reaction it can be exothermic or endothermic. ΔHr (molar heat of reaction) negative (indicating an exothermic reaction) or positive (indicating an endothermic reaction

Is exothermic reaction has positive or negative charge?


What is know about a reaction with a negative enthalpy?

-ve enthalphy mean exothermic process.

How do you know if a reaction is entropy driven enthalpy driven or driven by both enthalpy and energy?

If the ∆H is positive and the ∆S is positive, then the reaction is entropy driven. If the ∆H is negative and the ∆S is negative, then the reaction is enthalpy driven. If ∆H is positive and ∆S is negative, then the reaction is driven by neither of these. If ∆H is negative and ∆S is positive, then the reaction is driven by both of these.

What is the sign of ฮ”T in an endothermic reaction?

ΔH is the enthalpy of the reaction and will be positive in an endothermic reaction and negative in an exothermic reaction.ΔT designates a change in temperature. T2-T1 = ΔTOften the change in temperature will be negative for an endothermic reaction.

Is exothermic negative or positive heat?

exothermic heat is negativeA different opinion:Heat itself cannot be negative. An exothermic reaction is a chemical reaction wherein a substance gives up heat. Since the substance is giving up energy in the form of heat, the enthalpy change of the substance is negative.

What type of reaction is exothermic reaction?

The reaction in which energy is being released, and the overall energy change (enthalpy) is negative.

What kind of enthalpy change favors a spontaneous reaction?

An exothermic reaction is a chemical reaction that releases energy in the form of heat. It favors a negative enthalpy change.

What is enthalpy?

enthalpy is the heat involved in a reaction - apex

What is heat of reaction and enthalpy of reaction?

Heat of reaction and enthalpy of reaction are the same thing. Enthalpy, or the heat transfer, cannot be measured, however we can measure the CHANGE of enthalpy which is shown by a value of ∆H. This measured in kilojoules per mole of reactant. (KJ/mol)This value may be positive or negative. For endothermic reactions (which absorb heat), the ∆H value is always positive. For exothermic, where heat is released, the value is negative.

How does the enthalpy of the products compare with the enthalpy of the reactants in an exothermic reaction?

In an exothermic reaction heat is released, so the enthalpy of the products would be lower than the enthalpy of the reactants because it is losing energy.

Why is the enthalpy change of combustion always negative?

It is and exothermic reaction, which means energy is given out heating the surroundings.

When enthalpy in a system increases what is the reaction considered to be?


Why is neutralization exothermic?

neutralization is exothermic because the reaction of the strang base and strong acid produces heat. In other words, if you take the enthalpy of the products minus that of the reactants, you will find that the overall enthalpy is negative. Hope that helps!

In term of energy changes during bond breaking and bond forming when so you have exothermic reactions?

The enthalpy change associated with a reaction = sum of (energies of bonds broken) - sum of (energies of bonds formed). Thus, if this value is net negative, the reaction is exothermic; the products are also more stable than the reactants (lower-energy bonds). A positive enthalpy indicates an endothermic reaction.

In an exothermic reaction is the energy of the product higher or lower than the reactants?

In an exothermic reaction, the energy (or rather enthalpy) of the products is less than the energy (enthalpy) of the reactants. Energy has been released.

How is enthalpy related to the sponteneity of a reaction?

Enthalpy is one of the factors involved in calculating the Gibbs free energy, which determines the spontaneity of a reaction. Gibbs free energy change = Enthalpy change - absolute temperature x entropy change. If the Gibbs free energy change is negative then the reaction is spontaneous. This depends on the balance between enthalpy and entropy changes, and also the temperature. The enthalpy change is negative when the reaction is exothermic, and this obviously favours spontaneity, but it is not sufficient alone.

What does it mean if the change in enthalpy value for a chemical reaction is positive?

Change in enthalpy value for a chemical reaction is positive is because,there loose of electron(s) in the reaction, and that will change the enthalpy of that particular element from negetive,neutral to positive.

What does a negative deltaH tell about a reaction?

the reaction is exothermic

What does a negative H tell about a reaction?

The reaction is exothermic.