Heat Flow Calculator

Understanding Heat Flow Calculator

Heat flow (Q) is the thermal energy transferred due to temperature difference. Specific heat capacity (c) is the energy needed to raise 1 kg by 1 K.

How to use this calculator

1. Enter the mass of the substance as well as its specific heat capacity.
2. Enter the starting and ending temperatures so you can find the temperature change \(\Delta T\).
3. Check that your units are consistent, such as grams or kilograms for mass and \(\degree\mathrm{C}\) or K for temperature change.
4. Compute the heat flow with \(Q = mc\Delta T\).

The formula explained

The formula \(Q = mc\Delta T\) computes the heat energy \(Q\) needed to change a substance's temperature. Here, \(m\) is mass, \(c\) is specific heat capacity, and \(\Delta T\) is the temperature change.

• Q = heat energy transferred
• m = mass of the substance
• c = specific heat capacity
• \(\Delta T\) = change in temperature, found by \(T_{final} - T_{initial}\)

Step by step method

1. Find the temperature change with \(\Delta T = T_{final} - T_{initial}\).
2. Multiply the mass by the specific heat capacity.
3. Multiply that result by \(\Delta T\) to get \(Q\).

Worked example

Problem. A 2 kg block of aluminum with specific heat capacity \(900 \; \mathrm{J/(kg\cdot {}^{\circ} C)}\) is warmed from \(20 {}^{\circ}\mathrm{C}\) to \(35 {}^{\circ}\mathrm{C}\). Find the heat flow.

1. First find the temperature change, \(\Delta T = 35 - 20 = 15 {}^{\circ}\mathrm{C}\).
2. Use \(Q = mc\Delta T\): \(Q = 2 \times 900 \times 15\).
3. Compute the result, \(Q = 27{,}000 \; \mathrm{J}\).

Tips and common mistakes

• Use the temperature difference, not the two temperatures added together.
• If the substance cools down, \(\Delta T\) is negative, so \(Q\) is negative too.

Frequently asked questions