# High School Physics : Understanding Enthalpy

## Example Questions

### Example Question #31 : Thermodynamics

Enthalpy is a measure of __________.

Possible Answers:

how easily something changes temperature

the conversion of energy to heat

total energy of a thermodynamic system

total energy lost in heat transfer

total work done by a thermodynamic system

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 #32 : Thermodynamics

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

Possible Answers:

The temperature of the mixture steadily decreases while melting.

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

It remains constant while melting.

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

The temperature of the mixture steadily increases while melting.

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.