(3) Relationship between quantity of state and energy

What represents a state of a substance such as pressure, temperature and volume is called quantity of state.
In addition to these there are various quantities of state such as enthalpy, entropy, internal energy and so on.
What is generated by a change of state such as quantity of heat, power and work, etc. are not quantity of state.
These are energy that the substance brings in from the surrounding or takes out to it. It is also called external energy.
In the example of (2), the quantity of heat of 4.186 kJ is an external energy.
On the other hand, when it is said that specific enthalpy (or internal energy) is higher by 4.186 kJ/kg per 1��, this is a description as state of energy.