How do you make a heating curve?

Plot temperature on the y-axis and heat added on the x-axis. Draw a rising line for the solid, a flat plateau at the melting point, a rising line for the liquid, a flat plateau at the boiling point, and a rising line for the gas. This generator draws all five segments and the plateaus for any melting and boiling point, and exports SVG or PNG — free.

Why does the temperature stay constant during melting and boiling?

During a phase change the added heat breaks the attractions between particles instead of increasing their kinetic energy, so the temperature does not change. This energy is the latent heat (heat of fusion for melting, heat of vaporization for boiling), which is why the curve is flat there.

Is a heating curve the same as a phase change diagram?

Yes — "phase change diagram" is commonly used to mean a heating (or cooling) curve, a plot of temperature versus heat added with plateaus at the phase changes. (Note that some courses also use "phase diagram" for the separate pressure–temperature diagram.)

What is the difference between a heating curve and a cooling curve?

A heating curve shows temperature rising as heat is added, with plateaus at melting and boiling. A cooling curve shows temperature falling as heat is removed, with plateaus at condensing and freezing. Use the direction toggle to switch between them.

What do the slopes and plateaus represent?

On the sloped sections, added heat raises the temperature (kinetic energy of particles increases). On the flat plateaus, added heat drives a phase change at constant temperature (potential energy changes as bonds break). The vaporization plateau is longer because vaporization requires more energy than melting.

Can I make a heating curve for any substance?

Yes. Enter any melting point and boiling point, or pick a preset like water or iron. The tool plots the curve with plateaus at those temperatures and lets you export it for homework, worksheets, or slides.

Chemistry Tool

Heating Curve Generator & Phase Change Diagram Maker

Make a heating or cooling curve (phase change diagram) in seconds. Plot temperature vs heat added with flat plateaus at the melting and boiling points, label the solid, liquid, and gas phases, and export SVG or PNG — free.

Temperature vs heat addedMelting & boiling plateausHeating or cooling · any substanceSVG & PNG export — free

Substance

Melting point (°C)Boiling point (°C)

Direction

Title

Flat plateaus mark phase changes: melting at 0°C and boiling at 100°C, where temperature stays constant while heat is absorbed.

Heating Curve Examples

Heating and cooling curves rendered by the exact engine

Vista:

Heating Curve of Water

Temperature rises, then stays flat at 0°C (melting) and 100°C (boiling) while heat is absorbed.

waterheatingplateaus

Cooling Curve of Water

A cooling curve mirrors heating — plateaus mark condensing and freezing.

watercooling

Phase Change Diagram

Set any melting and boiling point — also called a phase change diagram.

genericphase-change

Phase Change Segments

Every segment labeled: warming the solid, melting, warming the liquid, boiling, warming the gas.

phase-changelabeled

Heating Curve of Iron

Works for any substance — here iron, melting at 1538°C and boiling at 2862°C.

ironhigh-temp

Cooling Curve with Phase Changes

Flip to a cooling curve to show condensing and freezing as heat is removed.

coolinglabeled

What is a heating curve?

A heating curve is a graph of temperature versus heat added as a substance is warmed from a solid to a liquid to a gas. It has five parts: the solid warming up, a flat plateau while it melts, the liquid warming up, a flat plateau while it boils, and the gas warming up. The flat plateaus are where a phase change happens — the temperature stays constant even though heat is still being added. It is also called a phase change diagram.

Why are there flat plateaus on a heating curve?

During a phase change (melting or boiling), the added heat goes into breaking the forces between particles rather than raising their kinetic energy, so the temperature stays constant. This heat is the latent heat — the heat of fusion for melting and the heat of vaporization for boiling. The longer vaporization plateau reflects the larger heat of vaporization. On the sloped sections, the heat raises the temperature instead.

The five segments of a heating curve

Warming the solid: temperature rises until the melting point.
Melting plateau: solid → liquid at the melting point, temperature constant.
Warming the liquid: temperature rises until the boiling point.
Boiling plateau: liquid → gas at the boiling point, temperature constant.
Warming the gas: temperature rises again.

Heating curve vs cooling curve

A cooling curve is the reverse of a heating curve: as heat is removed, the gas cools, condenses (plateau), the liquid cools, freezes (plateau), and the solid cools. The plateaus occur at the same temperatures as melting and boiling but represent condensing and freezing. Use the direction toggle to switch between a heating curve and a cooling curve.

Heating curve vs phase diagram

A heating curve plots temperature against heat added at constant pressure, showing when phase changes happen as you add energy. A P–T phase diagram instead plots pressure against temperature to show which phase is stable at each combination. They are complementary — for the pressure–temperature version, use the phase diagram generator.

When to use the AI illustration mode

Use the exact Heating curve mode for a correctly-plateaued temperature-vs-heat graph for any substance. Switch to AI illustration for richly annotated versions — with particle diagrams of each phase, heat of fusion and vaporization labels, or kinetic-vs-potential-energy annotations.