All calculatorsHeat Transfer Calculator (q = m c ΔT)
Compute heat q, mass m, specific heat c, or temperature change ΔT using q = m c ΔT. Supports common units (J, kJ, cal; g, kg; J/g·K, J/kg·K, cal/g·°C) and lets you enter ΔT directly or from initial/final temperatures.
Background
The heat equation q = m c ΔT relates the heat transferred q to a substance’s mass m, specific heat capacity c, and temperature change ΔT. A positive q indicates heat absorbed (warming); negative q indicates heat released (cooling). For temperature changes, ΔT in °C is numerically equal to ΔT in K.
How to use this calculator
- Choose what to solve for (q, m, c, or ΔT). Enter the remaining known variables.
- Enter ΔT directly or provide initial and final temperatures (ΔT = Tf − Ti).
- Match units sensibly; the tool converts internally (J↔kJ↔cal; g↔kg; J/g·K↔J/kg·K↔cal/g·°C).
Example Problems & Step-by-Step Solutions
Example 1 (Solve q)
Heat 125.0 g of water by 15.0 °C. Using c = 4.184 J/g·K:
q = (125.0 g)(4.184 J/g·K)(15.0 K) = 7,845 J ≈ 7.845 kJ.
Example 2 (Solve ΔT)
A 250 g aluminum block (c = 0.897 J/g·K) absorbs 1.80 kJ.
ΔT = q/(m c) = 1,800 J / (250×0.897) ≈ 8.02 K.
Frequently Asked Questions
Q: What does the sign of q mean?
Positive q: heat absorbed (warming). Negative q: heat released (cooling).
Q: Should ΔT be in °C or K?
ΔT in °C is numerically the same as ΔT in K. Use either; the calculator handles it.
Q: Can this handle phase changes?
Phase changes require enthalpy of fusion/vaporization, not q = m c ΔT. This tool is for temperature changes within a phase.
Q: My specific heat is in J/kg·K—will it work?
Yes. Choose J/kg·K and the tool will convert units consistently.
