ENTHALPY

WHAT IS ENTHALPY ?

Enthalpy is a thermodynamic property of system , it is the sum of the internal energy added to the product of the pressure and volume of the system

 H = E +(PV)

where , H = enthalpy

             E = internal energy 

             P = pressure

             V = volume

• It reflects the capacity to do no mechanical and capacity to release heat .
• Enthalpy is denoted by H & the specific enthalpy is denoted by h .
• Common units are used to express enthalpy are Joule's , colorie , BTU ( british thermal unit)
• Enthalpy is constant in throatling process
• Eenthalpy of system measurement is possible to measure the difference between in enthalpy between one state and another

IMPORTANCE OF ENTHALPY

• It is used to calculate the head of reaction of a chemical process
• measuring the change in enthalpy , to determine wheather a reaction was endothermic ( absorbed heat positive change in enthalpy ) OR exothermic ( released heat , negative change in enthalpy)

• change in enthalpy is used to measure heat process or joule's - thomson expansion
• enthalpy is also used to calculate minimum power for a compressor
• enthalpy changes when change in state of matter