Beginner Topic 266 of 1102 States of Matter & Solutions
Heating Curve
A graph of temperature versus heat added showing plateaus at phase changes.
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In-depth explanation of Heating Curve
A heating curve is a graph of temperature against the total heat added to a substance, showing how the substance changes with energy input. Sloped regions correspond to heating a single phase, where the heat absorbed is q = m c ΔT and the temperature rises. Flat plateaus correspond to phase changes, where the added energy is used to break intermolecular forces, so q = m ΔH and the temperature stays constant. The length of each plateau reflects the enthalpy of the phase change, which is larger for vaporization than for fusion. Heating curves help explain energy changes in calorimetry and in phase transitions.
Going deeper: Heating Curve
Key ideas: Calculation steps: sum q for each segment. For 1 g ice from -20 C to steam at 120 C: ice warming 2.09 x 20 = 42 J, melting 334 J, water warming 418 J, boiling 2260 J, steam warming 2.01 x 20 = 40 J, total about 3.1 kJ. Slopes are inversely related to specific heats, so steam rises steeply and water more gently.
Common mistakes and connections: The usual mistakes are applying q = m c ΔT across a phase change, or using the same specific heat for every phase. Another is mixing up which plateau is longer; vaporization is longer than fusion. Cooling curves are the reverse. Related to enthalpy of fusion, vaporization, calorimetry and supercooling.
Visualization of Heating Curve
Heating curve: temperature rises on slopes and stays flat during melting and boiling while heat goes into changing phase, not temperature. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Heating ice at -20°C to steam at 120°C produces five segments: warming ice, melting, warming water, boiling and warming steam.
Frequently asked questions about Heating Curve
What is Heating Curve?
A graph of temperature versus heat added showing plateaus at phase changes.
Is Heating Curve a beginner, intermediate or advanced topic?
Heating Curve is a beginner topic in States of Matter & Solutions. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Heating Curve?
Study these earlier topics in States of Matter & Solutions first: Meniscus, Enthalpy of Vaporization, Enthalpy of Fusion.
What comes after Heating Curve?
The next topics in States of Matter & Solutions are Sublimation and Deposition.
Can I practise Heating Curve with quizzes?
Yes. The interactive lesson includes a self-check question on Heating Curve, and the States of Matter & Solutions quiz draws on every topic in this area.
Where Heating Curve fits in States of Matter & Solutions
Heating Curve is topic 47 of 109 in States of Matter & Solutions.