Enthalpy Calculator
Calculate enthalpy change from heat transfer at constant pressure with mass, specific heat, and temperature change.
What Is Enthalpy Change?
Enthalpy change (\(\Delta H\)) measures the heat transferred at constant pressure during heating, cooling, or a phase change. For many practical problems, especially heating a substance, you can estimate \(\Delta H\) from mass, specific heat capacity, and temperature change without balancing a full chemical equation.
Enthalpy Change Formula
$$\Delta H = m \times c_p \times \Delta T$$Here \(m\) is mass in kilograms, \(c_p\) is specific heat capacity in J/(kg·K), and \(\Delta T\) is temperature change in kelvin (or degrees Celsius, since the size of one degree is the same). A positive result means heat was absorbed (endothermic); a negative result means heat was released (exothermic).
Choosing Specific Heat
Water has a high specific heat of about 4,186 J/(kg·K), which makes it slow to warm or cool. Metals such as copper and aluminum have lower values and heat up faster for the same energy input. Pick a preset material or enter a custom \(c_p\) for your substance.
Related tools: Specific Heat Calculator and Heat Capacity Calculator.
Frequently Asked Questions
What does a positive enthalpy change mean?
A positive \(\Delta H\) means the system absorbed heat from its surroundings. The process is endothermic.
Can I use degrees Celsius for temperature change?
Yes. A change of 20 °C equals a change of 20 K because the degree sizes match. Only temperature differences work this way, not absolute temperatures on the Fahrenheit scale without conversion.
Is this the same as chemical reaction enthalpy?
This calculator uses the sensible heat formula for temperature change. Standard enthalpies of formation for chemical reactions use a different approach based on products minus reactants.
Why does water need so much energy to heat?
Water's specific heat is about 4,186 J/(kg·K), much higher than most metals. That is why lakes moderate local climate and why pots of water take time to boil.
What pressure does this formula assume?
The \(\Delta H = mc\Delta T\) form assumes constant pressure, which is typical for open-container heating and many lab calorimetry setups.
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