change of heat in a reaction is the change in enthaply, the energy evolved or consumed obviously in a reaction is termed as enthalpy change in modern chemistry .
Sublimation enthalpy/ Heat of sublimation.
The energy consumed by one mole of solid substance to convert directly from solid to gaseous state is known as sublimation enthalpy.
Its a one step process if we make it 2 then there may be a change in enthalpy will happen, And is considered as wrong.
Sublimation reaction is a endothermic reaction as there is the consumption of heat energy .
C (s) ➡ C (g) 🔺H=+717.02kj/mol
Here sublimation enthalpy of C is 717.02kj/mol.
Ionisation enthalpy/ heat of ionisation
In gaseous state the energy consumed by one mole of any nutral substance to convert it into one mole of positively charged ion is known as ionisation energy.
I.e the energy consumption for bring out the outermost orbital electron from a nutral substance. Is also an endothermic process enthalpy change is positive .
Na ➡ Na+ + e– 🔺H= 494kj/mol
Atomization energy/Atomization enthalpy
The amount of energy consumed by one mole of any substance to convert it into gaseous atom .
I.e the liquid substance consumed an amount of heat energy and the enthalpy change is the vaporization enthalpy.
The energy consumption by Cl in atomization is +121kj/mol.
1/2 Cl2(g) ➡ Cl (g)
here a things to highlight the energy consumption is not by one mole of Cl molecule but one mole of Cl atom.
Vaporization enthalpy/ heat of vaporization
The energy consumption by one mole of any liquid substance to convert it into one mole of gaseous substance at 1 atm pressure .
Liquid water consumes +41 kj/mol in its boiling point to convert it into gaseous water vapour.
H2O (l) ➡ H2O (g)
Heat of Fusion/ Fusion enthalpy
The energy required to convert a solid substance into liquid, obviously the heat of fusion is different for different substances, also a characteristics property of any substance.
H2O (l) ➡ H2O(g) 🔺H=+6 kj/mol
Electron affinity / Electron affinity enthalpy.
The amount of energy released for one mole of any nutral gaseous atom to convert it into one mole of negatively chaged gaseous atom, that means the addition of one mole electron to one mole nutral gaseus substance.
This is an exothermic process.
For example
Cl(g) ➡ Cl- (g) 🔺H=-348kj/mol
Lattice enthalpy
The energy evolved at the last stage of an ionic bond formation the required amount of gaseous ions from infinit distance to get them together for the formation of a solid lattice.
In other words the energy evolved in the formation of a lattice from the isolated gaseous inagurent atoms.
As energy is evolved in this process the change is exothermic and enthalpy change must be negative in value.
K+ + Cl- ➡ KCl 🔺H=-760kj/mol
Heat of combustion/ combustion enthalpy
At a certain themperature and 1 atm pressure change in enthalpy for completly burning 1 mol substance by oxygen is known as combustion enthalpy.
And the energy evloved in burning of any 1 mol substance by oxygen at 25°c and 1 atm is known as heat of standard combustion / standard combustion enthalpy.
C + O2 ➡ CO2 🔺H=-395kj/mol
Neutralization enthapy / heat of nutralization.
At 25°c and 1 atm the heat energy evloved in a chemical reaction of an acid and a base to produce one mole of water is known as heat of nutralization , the enthalpy change is known as nutralization enthalpy
The nutralization reaction of HCl and NaOH to produce one mole of water is with evolving of 57.34 kj/mol
HCl+ NaOH ➡NaCl+H2O
🔺H=57.34kj/mol
Normally the nutralization of strong acid and base occured with evolvin 57.34kj/mol.
Heat of solution/ solution enthalpy
At a cetain temperature if one mole of any solute is solvated into a sovent and after adding more solvent to that solution and no change in the temprature of the solution then the temperature change is termed as heat of solution.
The heat of solution depend on the nature of the solute and solvent if there is any reaction occured Then enthalpy change will be positive in value and if no reaction occured then enthalpy change will negative in value.
The hydration of CuSO4 is an example.
CuSO4 + H2O➡ CuSO4. 5H2O
🔺H =-66kj/mol.
Bond enthalpy/ Bond Energy
At gaseous state to break the bond between two atom of any molecule
i.e the amount of energy required to break 6.02×10^23 bond between to atom of a molecule.
M-O ➡ M(g) + O(g) 🔺H=....
Breaking of bond M-O causes the formation of free radical M and O.
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