Enthalpy Calculations Made Easy | Extensive Property & Sign Change | Thermochemistry Class 11

Hinzugefügt: 2026-05-07

[00:00:00]Delta r h [music] 1 theta is equal to 3 * 285.83 kJ [music] per mole inverse 1 * -824.2 [music] kJ per mole inverse.

[00:00:19]That is equal to -857.5 [music] + 824.2 [music] kJ per mole inverse. That is equal to [music] -33.3 kJ per mole inverse. 1/2 of Fe2O3 + [music] 3/2 of H2 gives rise to Fe + [music] 3/2 of H2O.

[00:00:46]If we calculate the delta r h theta [music] value for this, delta r h 2 theta is [music] equal to 3/2 * -285.83 1/2 * -824.2. [music] That is equal to -428.7 [music] + 412.1 [music] kJ per mole inverse, which is equal to -16.6 kJ per mole inverse. [music] That is equal to 1/2 of delta r h 1 theta.

[00:01:26]From this, we understand that enthalpy is [music] an extensive property.

[00:01:32]If we write the chemical reaction in reverse, the sign of delta r [music] h theta changes.

[00:01:39]Example, N2 + [music] 3 H2 gives rise to 2 NH3.

[00:01:46]Delta r h theta is equal [music] to -91.8 kJ.

[00:01:54]>> [music] >> 2 NH3 gives rise to N2 + 3 H2.

[00:02:01]Delta r h theta is equal [music] to +91.8 kJ.