Chapter 6 (section 6) Flashcards
the enthalpy of a system is …?
the sum of its internal energy and the product of its pressure and volume
H = U + PV
What is the equation for the change of the enthalpy of a system?
ΔH = ΔU + PΔV
Define exothermic reaction
a chemical reaction that releases heat into its surroundings; for an exothermic reaction, ∆H < 0
A positive ΔH indicates …?
heat flows into the system as the reaction occurs
A negative ΔH indicates …?
heats flows out of the system as a reaction occurs
A positive ΔH means the reaction is _____
endothermic
A negative ΔH means the reaction is ___
exothermic
Define endothermic reaction
a chemical reaction that absobrbs heat from its suroroundings; for an endothermic reaction, ∆H > 0
What is symbol the enthalpy change of a reaction?
ΔᵣH
The enthaply change of reaction is also called _____ __ ____ or ____ ____
enthalpy of reaction
heat of reaction
Define heat of reaction
the enthalpy change for a chemical reaction
Define entahlpy of reaction
the enthalpy change for a chemical reaction
The enthalpy of the reaction is a ____ property. This means it depends on…?
extensive
the amount of material undergoing the reaction.
Define enthalpy (H)
The sum of the internal energy of a system and the product of its pressure and volume; the energy associated with the breaking and forming of bonds in a chemical equation
Since internal energy, pressure, and volume are all state functions, enthaply is….?
also a state function
If pressure is constant, what is the change in enthalpy equal to?
Temperature
The value of ∆ᵣH for a chemical reaction is….?
the amount of heat absorbed or evolved in the reaction under conditions of constant pressure
Where does energy come from in an exothermic reaction seeing as both the temperature of the system and the surroundings rises?
The energy comes from bonds breaking and the forming in a way which lowers the potential energy of the system.
Where does the energy go in an endothermic reaction seeing as both the temperature of the system and the surroundings drops?
The energy goes into breaking bonds and then forming bonds of higher potential energy increasing the potential energy of the system.
