Convert moles to kJ by multiplying the amount in moles by the molar enthalpy change in kJ/mol, or work back from kJ to moles or to kJ/mol.

Use ฮ”H for your reaction’s mole basis. Positive ฮ”H means heat absorbed; negative means heat released.

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Moles to kJ Formula

The following formula is used to calculate the energy in kJ for a given number of moles and enthalpy change.

E = n ร— ฮ”H

Variables:

  • E is the energy in kilojoules (kJ)
  • n is the number of moles
  • ฮ”H is the enthalpy change in kilojoules per mole (kJ/mol)

To calculate the energy, multiply the number of moles by the enthalpy change.

Moles to Energy Conversion Table (ฮ”H = -285.83 kJ/mol, Formation of H2O(l))
Moles (mol) Energy (kJ) Energy (J) Energy (cal) Energy (BTU)
0.001-0.286-286-68.315-0.271
0.005-1.429-1429-341.575-1.355
0.01-2.858-2858-683.150-2.709
0.02-5.717-5717-1366.300-5.418
0.025-7.146-7146-1707.875-6.773
0.05-14.292-14292-3415.750-13.546
0.075-21.437-21437-5123.626-20.319
0.1-28.583-28583-6831.501-27.091
0.2-57.166-57166-13663.002-54.183
0.25-71.458-71458-17078.752-67.729
0.5-142.915-142915-34157.505-135.457
0.75-214.373-214373-51236.257-203.186
1-285.830-285830-68315.010-270.915
1.5-428.745-428745-102472.514-406.372
2-571.660-571660-136630.019-541.829
2.5-714.575-714575-170787.524-677.286
3-857.490-857490-204945.029-812.744
4-1143.320-1143320-273260.038-1083.658
5-1429.150-1429150-341575.048-1354.573
10-2858.300-2858300-683150.096-2709.146
Assumes enthalpy change ฮ”H = -285.83 kJ/mol (formation of liquid water at 25ยฐC). Negative sign indicates heat released (exothermic). Energy conversions used: 1 kJ = 1000 J โ‰ˆ 239.005736 thermochemical cal โ‰ˆ 0.947817120 BTU (International Table).

Convert kJ/mol or kJ/kmol to kJ/kg

Choose Convert molar enthalpy to convert between kJ/mol, J/mol, thermochemical cal/mol, kcal/mol, kJ/kmol and BTU/mol. Enter molar mass to show the mass-specific enthalpy change in kJ/kg as the main result. If molar mass is blank, the calculator converts molar units only.

Mass-specific enthalpy (kJ/kg) = molar enthalpy (kJ/mol) ร— 1,000 รท molar mass (g/mol). First divide a value in kJ/kmol by 1,000 to obtain kJ/mol. Equivalently, a value in kJ/kmol divided by molar mass in kg/kmol gives kJ/kg; the numerical molar mass in kg/kmol is the same as in g/mol.

For example, โˆ’100 kJ/mol and a molar mass of 50 g/mol give โˆ’2,000 kJ/kg. The same molar value is โˆ’100,000 kJ/kmol. The negative sign is retained. Use the molar mass of the same substance and mole basis as the enthalpy value; a reaction enthalpy per mole of reaction cannot be assigned to an arbitrary substance mass.

These conversions use the thermochemical calorie: 1 cal = 4.184 J exactly, so 1 kcal/mol = 4.184 kJ/mol. Converting units does not change the temperature, pressure or reference state of the original enthalpy value.

What is Moles to kJ?

The moles to kJ calculation is used to determine the amount of energy in kilojoules (kJ) for a given number of moles and enthalpy change. This is particularly useful in chemistry when dealing with reactions and energy changes. The enthalpy change (ฮ”H) represents the heat absorbed or released during a reaction per mole of substance.

How to Calculate Moles to kJ?

The following steps outline how to calculate the energy in kilojoules from moles and enthalpy change.

  1. First, determine the number of moles (n).
  2. Next, determine the enthalpy change (ฮ”H) in kJ/mol.
  3. Finally, calculate the energy using the formula E = n * ฮ”H.
  4. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Number of moles (n) = 2

Enthalpy change (ฮ”H) = 50 kJ/mol