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Question: What’s the unit of enthalpy?...

What’s the unit of enthalpy?

Explanation

Solution

Hint : We know that the start by using the mathematical expression for calculation of entropy. Enthalpy is calculated by taking into consideration the temperature and heat of the system. Enthalpy is the measure of the total energy of a system. Also, for work done by the system on the surroundings, the value of w is negative (−w)\left( -w \right) .

Complete Step By Step Answer:
Enthalpy is a thermodynamic state function. In simple language, you can also take it to be a measure of heat in the system. It is the sum of the system's internal energy, U and the product of its pressure, P and volume, V. The product of volume and pressure is work, W. Enthalpy is denoted by H. The formula is H=U+PVH=U+PV
Where, U is the internal energy of the system.
P is the pressure of the system.
V is the volume of the system.
For the second part, if the system performs work on the surroundings, the internal energy of the system decreases. This implies that the system will use its own energy to do work and as a result, there is a decrease in internal energy. Internal energy is given as ΔU=q+w\Delta U=q+w
For the second part, if the system performs work on the surroundings, the internal energy of the system decreases. This implies that the system will use its own energy to do work and as a result, there is a decrease in internal energy. Also, temperature (T) is a measure of average chaotic motion of particles in the system. The randomness is more Heat added to a system at lower temperature causes more randomness than when it is heated at higher temperature. Therefore, we can say S is indirectly proportional to T. Hence, the relation between S, q and T for a reversible reaction is given as
S=qrevTS={{q}_{rev}}T
SI unit of heat (q) =Jmol−1=Jmo{{l}^{-1}}
SI unit of temperature (T) =k=k
SI unit of Enthalpy =kJmol−1=kJmo{{l}^{-1}}

Note :
Remember that in a system is in equilibrium, the entropy is maximum, and the change in entropy is zero. Hence, we can say that S for a spontaneous process increases till it reaches a maximum and at equilibrium, the change in entropy is zero.