Q1. How much heat is needed to convert 1 kg of ice at 0 °C to water at 0 °C? (L = 3.36×10⁵ J/kg)
During melting the temperature stays at 0 °C (latent heat)
Q = mL = 1 × 3.36×10⁵
Q = 3.36×10⁵ J
Thermal Properties of Matter — Class 11
How much heat warms a kettle or melts ice? Learn specific and latent heat and thermal expansion, and compute heat instantly.
Heat & temperatureHeat is energy transferred due to a temperature difference (joule); temperature measures the average kinetic energy (kelvin/°C).
Specific heat capacityThe heat to raise 1 kg by 1 °C: Q = m·c·ΔT. Water has a very high c (4200 J/kg·°C).
Latent heatHeat absorbed/released during a change of state, at constant temperature: Q = m·L.
Thermal expansion & transferSolids/liquids expand on heating (ΔL = αLΔT). Heat travels by conduction, convection and radiation.
Heat calculator (Q = mcΔT) Interactive
Enter the mass, specific heat and temperature rise to find the heat required.
Heat, Q = mcΔT—J
Water's high specific heat is why it is used as a coolant and why coastal climates are mild.
Numericals practice Interactive
Specific-heat and latent-heat problems with steps.
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Solved numericals
Q2. A 500 g metal block cools from 100 °C to 20 °C, releasing 16000 J. Find its specific heat.
Q = mcΔT ⇒ c = Q/(mΔT)
c = 16000 / (0.5 × 80)
c = 400 J/kg·°C
Formula sheet
| Quantity | Formula | SI unit |
|---|---|---|
| Heat for temperature change | Q = m c ΔT | joule (J) |
| Heat for change of state | Q = m L | J |
| Linear expansion | ΔL = α L ΔT | m |
| Specific heat of water | c = 4200 J/kg·°C | J/kg·°C |
Common mistakes & exam wins
- During a change of state the temperature stays constant — the heat goes into latent heat.
- Water's specific heat (4200 J/kg·°C) is unusually high, moderating climate and cooling engines.
- Q = mcΔT for a temperature change; Q = mL for melting or boiling.
- The three modes of heat transfer are conduction (solids), convection (fluids) and radiation (no medium needed).
Frequently asked questions
What is specific heat capacity?
The amount of heat required to raise the temperature of 1 kg of a substance by 1 °C, related by Q = mcΔT.
What is latent heat?
The heat absorbed or released during a change of state at constant temperature, Q = mL.
What are the three modes of heat transfer?
Conduction (through solids without bulk motion), convection (bulk motion of fluids) and radiation (electromagnetic waves, needing no medium).