All of the following are properties of enthalpy EXCEPT: (Question from \"Crackin

ID: 929233 • Letter: A

Question

All of the following are properties of enthalpy EXCEPT: (Question from "Cracking the MCAT, 2010-2011 edition" by The Princeton Review)

the change in enthalpy of a system is equal to the change in its internal energy.

a negative change in enthalpy indicates that heat is lost to the surroundings.

a positive change in enthalpy indicates that heat is absorbed by the system.

a reaction with a negative change in enthalpy is exothermic, a reaction with a positive change in enthalpy is endothermic.

the change in enthalpy of a system is equal to the change in its internal energy.

a negative change in enthalpy indicates that heat is lost to the surroundings.

a positive change in enthalpy indicates that heat is absorbed by the system.

a reaction with a negative change in enthalpy is exothermic, a reaction with a positive change in enthalpy is endothermic.

we know that

a negative change in enthalpy indicated that heat is lost to the surroundings

this is also called exothermic reaction

also

a positive change in enthalpy indicates that heat is absorbed by the system

this is also called enodthermic reaction

a reaction with a negative change in enthalpy is exothermic

and

a reaction with a positive change in enthalpy is endothermic

now

the realtion between enthalpy and internal energy is given by

dH = dE + w

consider a constant volume process , w = 0

then

dH = dE

so for a constant volume process

change in enthalpy of a system is equal to change in its internal energy

but it is not true for all process

all the following are properties of enthalpy except

the change in enthalpy is equal to change in its internal energy

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