Understand and calculate the complete energy journey as matter transforms through all three phases — heating, melting, heating, boiling
Drag the slider to move through all phases
Calculate the total energy needed to take a substance from solid to gas
Enter parameters to calculate the total energy for the complete solid→liquid→gas process.
The solid absorbs heat and its temperature rises. Molecules vibrate faster but stay in their lattice positions. Uses the solid's specific heat capacity.
At the melting point, temperature plateaus. All energy goes into breaking the crystal lattice. The substance transitions from solid to liquid. Uses the latent heat of fusion.
The liquid absorbs heat, temperature rises again. Molecules move more freely but stay close together. Uses the liquid's specific heat capacity (usually higher than solid).
At the boiling point, temperature plateaus again. Energy breaks remaining intermolecular bonds. The substance becomes gas. This step usually requires the most energy.
The gas absorbs heat, temperature rises. Molecules are completely free, moving at high speeds. Uses the gas specific heat capacity.
Boiling must completely separate molecules from each other, overcoming all intermolecular forces. Melting only loosens the rigid crystal structure while keeping molecules close. For water: Lv = 2,260 kJ/kg vs Lf = 334 kJ/kg — nearly 7× more energy for boiling.
Each step requires energy input: sensible heating (Q₁, Q₃, Q₅) raises temperature using Q=mcΔT, while phase changes (Q₂, Q₄) use latent heat Q=mL at constant temperature. The total is the sum of all five steps.
Yes! If you start above the melting point, steps 1 and 2 are skipped. The calculator automatically detects which steps are needed based on your temperature range and only calculates relevant ones.
Below the triple point pressure, the liquid phase cannot exist. Instead of the 5-step process, the substance undergoes sublimation — a direct solid-to-gas transition in fewer steps. Use our Sublimation Calculator for that scenario.
With constant heating power, the step requiring the most energy takes the longest. For water, vaporization (Q₄) dominates, consuming about 75% of the total energy. This is why boiling a pot of water takes much longer than heating it to the boiling point.