High School Physics : Understanding Enthalpy

Study concepts, example questions & explanations for High School Physics

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Example Questions

Example Question #1 : Enthalpy And Entropy

Enthalpy is a measure of __________.

Possible Answers:

the conversion of energy to heat

total work done by a thermodynamic system

total energy lost in heat transfer

total energy of a thermodynamic system

how easily something changes temperature

Correct answer:

total energy of a thermodynamic system

Explanation:

Enthalpy, or , is the total energy of a thermodynamic system. Similar to how mechanical energy can change during mechanical processes, involving changing distances of velocities, enthalpy will increase or decrease with changes made to the thermodynamic state of the system. It is simply a measure for a different form of energy.

Example Question #2 : Enthalpy And Entropy

An ice cube melts into water. While it is melting, what is the temperature of the mixture doing?

Possible Answers:

The ice part of the mixture is colder than the water part.

The temperature of the mixture steadily increases while melting.

The temperature of the mixture steadily decreases while melting.

It remains constant while melting.

The temperature fluctuates depending upon the point at which you measure it.

Correct answer:

It remains constant while melting.

Explanation:

When an object is changing forms (solid to liquid in this case), the temperature remains constant. All of the energy that would normally go towards changing the internal temperature of the object is going into  the latent heat of fusion or enthalpy of fusion instead.

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