Why does a sandy beach burn your feet while the adjacent sea stays cool, even after the same hours of sunlight? Why does water make the ideal coolant in car engines? Why does a large pot take so long to boil? The answer is always the same: specific heat capacity. This property determines how much energy a substance must absorb per kilogram per degree of temperature change — and it varies enormously between materials.
Specific heat capacity (symbol c) is the energy required to raise 1 kg of a substance by 1 K (or 1°C). Formula: Q = mcΔT, where Q is heat energy (J), m is mass (kg), c is specific heat capacity (J/kg·K), and ΔT is temperature change (K or °C). Higher c means more energy required per degree of heating.
The Formula: Q = mcΔT
Rearranged forms:
Specific Heat Capacities of Common Materials
| Material | c (J/kg·K) |
|---|---|
| Water (liquid) | 4,186 |
| Ice | 2,090 |
| Steam | 2,010 |
| Aluminium | 897 |
| Iron / steel | 450 |
| Copper | 385 |
| Lead | 128 |
Worked Examples
Example 1: Heating water
Energy to heat 2 kg of water from 20°C to 100°C:
Example 2: Cooling copper
0.5 kg copper block cools from 120°C to 25°C:
Example 3: Finding c
0.2 kg unknown metal absorbs 1,800 J, temperature rises 50°C:
Close to tin (228 J/kg·K) or gold (129 J/kg·K) — the experiment helps identify the metal.
Why Water Has Such a High Specific Heat Capacity
Water's c = 4,186 J/kg·K — highest of all common liquids — arises from its hydrogen bonding network. Heating water requires energy both to increase molecular kinetic energy (raise temperature) and to disrupt hydrogen bonds. This bond energy acts as "hidden" thermal storage, dramatically increasing c relative to non-hydrogen-bonded liquids.
Practical consequences: oceans act as enormous thermal buffers, moderating coastal climates. Water's high SHC makes it the ideal coolant in car engines, nuclear reactors, and industrial heat exchangers.
Latent Heat: Phase Changes Without Temperature Change
Q = mcΔT applies only when temperature changes without phase change. During melting or boiling, temperature is constant while energy is still supplied — this goes into breaking intermolecular bonds:
where L is specific latent heat (J/kg). For water: L_fusion = 334,000 J/kg; L_vaporisation = 2,260,000 J/kg. Steam burns are far worse than boiling water burns at the same temperature: 1 kg of steam releases 2.26 MJ on condensing, before even cooling down.
Frequently Asked Questions
What is specific heat capacity?
The energy required to raise 1 kg of a substance by 1 K (or 1°C), measured in J/kg·K. High SHC means the material absorbs large amounts of heat with little temperature change. Water (4,186 J/kg·K) has the highest value of common liquids; metals are much lower.
What is the formula for specific heat capacity?
Q = mcΔT, where Q is heat energy (J), m is mass (kg), c is specific heat capacity (J/kg·K), and ΔT is temperature change (°C or K). Rearranged: c = Q/(mΔT) to find SHC; ΔT = Q/(mc) to find temperature change.
Why does water have a high specific heat capacity?
Water's extensive hydrogen bonding network requires energy to disrupt as well as to increase molecular motion. This extra energy storage dramatically raises SHC compared to non-hydrogen-bonded liquids, making oceans effective thermal buffers and water the ideal industrial coolant.
What is the specific heat capacity of water?
Liquid water: 4,186 J/kg·K (often approximated as 4,200). Ice: ~2,090 J/kg·K. Steam: ~2,010 J/kg·K — both roughly half of liquid water. The liquid phase value is exceptionally high and is the highest of all common substances.
What is the difference between specific heat capacity and latent heat?
SHC governs temperature change with no phase change: Q = mcΔT. Latent heat governs phase changes at constant temperature: Q = mL. Heating water from 0°C to 100°C uses SHC; boiling it uses latent heat of vaporisation (2,260 J/g) — far more energy than heating from 0°C to 100°C (418.6 J/g).
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Written by
Dr. Sarah KimThermodynamics researcher with a PhD from MIT, specializing in statistical mechanics and energy transfer. Passionate about connecting molecular physics to everyday phenomena.
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