1. What is the Energy Change Equation?

The energy change equation (ΔE = q + w) 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.

2. How Does the Calculator Work?

The calculator uses the energy change equation:

Where:

• \( \Delta E \) — Change in internal energy (joules)
• \( q \) — Heat transferred to/from the system (joules)
• \( w \) — Work done on/by the system (joules)

Explanation: The equation follows the first law of thermodynamics, conserving energy in thermodynamic processes.

3. Importance of Energy Change Calculation

Details: Calculating energy changes is fundamental in thermodynamics, helping understand energy transfers in chemical reactions, phase changes, and mechanical systems.

4. Using the Calculator

Tips: Enter both heat (q) and work (w) values in joules. Positive values indicate energy added to the system, negative values indicate energy removed from the system.

5. Frequently Asked Questions (FAQ)

Q1: What is the sign convention for q and w?
A: Positive q indicates heat added to the system. Positive w indicates work done on the system.

Q2: How does this relate to enthalpy?
A: At constant pressure, the enthalpy change (ΔH) equals the heat transfer (q).

Q3: What are typical units for energy change?
A: The SI unit is joules (J), though calories are sometimes used (1 cal = 4.184 J).

Q4: Can ΔE be negative?
A: Yes, a negative ΔE indicates the system has lost internal energy.

Q5: How is this equation used in real-world applications?
A: It's fundamental in engineering, chemistry, and physics for analyzing energy efficiency in processes and systems.