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Change in Energy Formula:
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The change in internal energy (ΔE) formula represents the first law of thermodynamics, stating that the change in internal energy of a system equals the heat added to the system plus the work done on the system.
The calculator uses the energy change formula:
Where:
Explanation: This fundamental thermodynamic equation describes energy conservation in chemical systems, where positive values indicate energy gained by the system and negative values indicate energy lost.
Details: Calculating energy changes is essential for understanding thermodynamic processes, predicting reaction spontaneity, and analyzing energy transformations in chemical systems.
Tips: Enter heat (q) and work (w) values in joules. Positive values indicate energy added to the system, negative values indicate energy removed from the system.
Q1: What is the sign convention for q and w?
A: q is positive when heat is added to the system, negative when heat is released. w is positive when work is done on the system, negative when the system does work on surroundings.
Q2: How does this relate to enthalpy (ΔH)?
A: For constant pressure processes, ΔH = q, making ΔE = ΔH + w. This relationship is fundamental in thermochemistry.
Q3: What are typical units for energy calculations?
A: Joules (J) are the SI unit, though kilojoules (kJ) are commonly used for larger energy values in chemical reactions.
Q4: When is ΔE equal to zero?
A: In isolated systems where no heat or work is exchanged with surroundings, ΔE = 0 according to the first law of thermodynamics.
Q5: How does this apply to real-world chemical processes?
A: This formula is used to calculate energy changes in reactions, phase transitions, and various thermodynamic processes in chemistry and engineering.