Asked by: Patrizia Guedes
science chemistry

What does a negative enthalpy mean?

Last Updated: 4th April, 2020

It is simply the amount of heat absorbed or releasedbythe reaction. Combustion reactions obviously release largeamountsof heat. They have negative enthalpy. Anegativeenthalpy represents an exothermic reaction,releasing heat. Areaction that absorbs heat isendothermic.

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Furthermore, what does a negative enthalpy value mean?

They can only measure changes in enthalpy.Whenenthalpy is positive and delta H is greater than zero,thismeans that a system absorbed heat. When enthalpyisnegative and delta H is less than zero, thismeansthat a system released heat. This is called anexothermicreaction.

Subsequently, question is, how do you know if enthalpy is positive or negative? Key Takeaways

  1. If ΔH is negative, the reaction is exothermic; ifΔHis positive, the reaction is endothermic.
  2. Thermochemical equations have the generalform:A+B→C,ΔH=(±n) A + B → C , Δ H =(± n ) .
  3. The value of enthalpy is dependent on the reactionconditions,as well as the concentration of reactants andproducts.

what happens when enthalpy is negative?

If ΔH is positive, the reaction isendothermic,that is heat is absorbed by the system due to theproducts of thereaction having a greater enthalpy than thereactants. Onthe other hand, if ΔH is negative, thereaction isexothermic, that is the overall decrease inenthalpy isachieved by the generation of heat.

How do you measure enthalpy?

Use the formula ∆H = m x s x ∆Ttosolve. Once you have m, the mass of your reactants, s,thespecific heat of your product, and ∆T, the temperaturechangefrom your reaction, you are prepared to find theenthalpy ofreaction. Simply plug your values into theformula ∆H = m x sx ∆T and multiply tosolve.

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