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Specific Heat Capacity Calculator

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Heat needed

334.7 kJ

334.7 kJ · 80 kcal · 317.3 BTU · 0.09298 kWh

Q = m × c × ΔT = 1,000 g × 4.184 J/(g·°C) × 80 °C = 334,700 J

takes at least 3.72 minutes; heat lost to the surroundings makes it longer.

Calculate the heat needed to warm or cool a material with Q = mcΔT, or solve for the mass, the specific heat or the final temperature, in joules, calories, BTU or kWh, with specific heats for water, metals and other common materials and the time a heater of a given power needs.

Formula

Q=m×c×ΔT\text{Q} = \text{m} \times \text{c} \times \Delta \text{T}
ΔT=Tfinal−Tstart\Delta \text{T} = \text{T}_{\text{final}} - \text{T}_{\text{start}}
c=Q÷(m×ΔT)\text{c} = \text{Q} \div (\text{m} \times \Delta \text{T})
heating time=Q÷power\text{heating time} = \text{Q} \div \text{power}

Worked Example

SubstanceWater, 4.184 J/(g·°C)
Mass1 kg (1 liter)
Temperature20 °C to 100 °C
Heater1,500 W kettle
Result
Heat needed334.7 kJ (80 kcal, 317 BTU, 0.093 kWh)
Heating timeat least 3.72 minutes

1,000 g × 4.184 J/(g·°C) × 80 °C = 334,720 J. A 1,500 W element delivers 1,500 J a second, so it needs 223 seconds even if no heat escapes; boiling the water away would take another 2,257 J per gram.

Frequently Asked Questions

What is specific heat capacity?

The energy needed to raise one gram of a material by one degree Celsius, or one kilogram by one kelvin. Water's is 4.184 J/(g·°C); most metals are far lower, such as aluminum at 0.897 and copper at 0.385, so they heat up and cool down much faster for the same energy.

Is a change of 1 °C the same as 1 K?

Yes. The two scales have the same size of degree and differ only in where zero is, so a temperature change is the same number in both. A change of 1 °C equals 1.8 °F.

Does Q = mcΔT work when ice melts or water boils?

No. During a phase change the temperature stays constant while the material absorbs latent heat: 334 J per gram to melt ice at 0 °C and 2,257 J per gram to boil water at 100 °C. Work out each stage separately, using the specific heat of ice, water or steam for the temperature changes.