Formula for Phase Change

Phase Change Equation:

\[ \Delta H = m \times L \]

Enthalpy Change (ΔH):

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1. What is the Phase Change Formula?

The phase change formula calculates the enthalpy change during a phase transition (such as melting, freezing, vaporization, or condensation). It represents the energy required or released when a substance changes from one state of matter to another.

2. How Does the Calculator Work?

The calculator uses the phase change equation:

\[ \Delta H = m \times L \]

Where:

\( \Delta H \) — Enthalpy change (Joules)
\( m \) — Mass of the substance (kilograms)
\( L \) — Latent heat of phase change (Joules per kilogram)

Explanation: The formula calculates the total energy involved in a phase transition by multiplying the mass of the substance by its specific latent heat value.

3. Importance of Enthalpy Calculation

Details: Accurate enthalpy calculation is crucial for understanding energy requirements in industrial processes, climate science, material science, and thermodynamic studies involving phase transitions.

4. Using the Calculator

Tips: Enter mass in kilograms and latent heat in Joules per kilogram. Both values must be positive numbers. Common latent heat values include 334,000 J/kg for ice melting and 2,260,000 J/kg for water vaporization.

5. Frequently Asked Questions (FAQ)

Q1: What is latent heat?
A: Latent heat is the energy absorbed or released during a phase change at constant temperature and pressure, without changing the substance's temperature.

Q2: What's the difference between latent and sensible heat?
A: Sensible heat changes temperature, while latent heat changes phase at constant temperature.

Q3: Why are there different latent heat values?
A: Different substances and different phase transitions (melting vs vaporization) have unique latent heat values based on their molecular properties.

Q4: Can this formula be used for all phase changes?
A: Yes, it applies to melting, freezing, vaporization, condensation, and sublimation, using the appropriate latent heat value for each transition.

Q5: What are typical units for enthalpy change?
A: Joules (J) in SI units, though kilojoules (kJ) are commonly used for larger quantities. In imperial units, British Thermal Units (BTU) are used.