This guide helps you easily convert between various enthalpy and entropy units used in thermodynamics. Whether you're working with kilojoules per kilogram (kJ/kg), BTU per pound (BTU/lb), kilojoules per mole (kJ/mol), calories per gram (cal/g), or joules per kilogram (J/kg), this tutorial provides the formulas and examples you need to make accurate conversions.
Entropy is a measure of the amount of disorder or randomness in a system. In thermodynamics, it is a quantitative measure of the irreversibility of spontaneous processes. Entropy is often described as a measure of energy dispersal in a system at a given temperature, and it reflects the tendency of natural processes to move towards a state of greater disorder or randomness.
In more technical terms, entropy (S) is defined as the change in heat divided by the temperature at which the change occurs:
S = ΔQ / T
where ΔQ is the heat added to the system, and T is the absolute temperature.
Entropy plays a crucial role in the second law of thermodynamics, which states that the total entropy of an isolated system always increases over time, leading to the concept of irreversibility in natural processes.
Formula: BTU/lb = kJ/kg * 0.4299
Example: Convert 100 kJ/kg to BTU/lb.
Solution: 100 kJ/kg * 0.4299 = 43.00 BTU/lb
Formula: kJ/mol = kJ/kg * Molar Mass (g/mol)
Example: Convert 10 kJ/kg to kJ/mol with Molar Mass = 18 g/mol.
Solution: 10 kJ/kg * 18 = 180 kJ/mol
Formula: J/kg = cal/g * 4,184
Example: Convert 0.5 cal/g to J/kg.
Solution: 0.5 cal/g * 4,184 = 2,092 J/kg
Formula: kJ/kg = BTU/lb * 2.326
Example: Convert 5 BTU/lb to kJ/kg.
Solution: 5 BTU/lb * 2.326 = 11.63 kJ/kg