Calculate the heat of combustion of ethane, in the reaction C2H6(g) + 3 1/2O2(g) → 2CO2(g) + 3H2O(l) where the heats of formation of ethane gas, carbon dioxide gas and water liquid are –84.7 kJ mol-1, -393.5 kJ mol-1 and –285.8 kJ mol-1 respectively.

Enthalpies for Different Types of Reactions are: 1.Heat of Formation : It is “The amount of heat evolved (or) absorbed during the formation of one mole of the compound at constant temperature from the constituent elements in the standard state. Eg : Heat or formation of CO2 C(s) + O2(g) →CO2(g) : ∆H = -393.5KJ   2. Enthalpy of fusion : The enthalpy change that accompanies melting of one mole of a solid substance in standard state is called enthalpy of fusion. H2O(s) →H2O(l) ; ∆H = 6.0KJ /mole    3, Enthalpy of Vapourisation : Amount of heat required to vapourise one mole of a liquid... Show more

Enthalpies for Different Types of Reactions are:

1.Heat of Formation : It is “The amount of heat evolved (or) absorbed during the formation of one mole of the compound at constant temperature from the constituent elements in the standard state.
Eg : Heat or formation of CO2
C(s) + O2(g) →CO2(g) : ∆H = -393.5KJ
 

2. Enthalpy of fusion : The enthalpy change that accompanies melting of one mole of a solid substance in standard state is called enthalpy of fusion.
H2O(s) →H2O(l) ; ∆H = 6.0KJ /mole 
 

3, Enthalpy of Vapourisation : Amount of heat required to vapourise one mole of a liquid at constant temperature and pressure is called its enthalpy of vapourisation.
 

4. Enthalpy of sublimation : The amount of heat required to convert one mole of a simple substance in the solid state into the gaseouos state without decomposition of the substance.
 

5. Enthalpy of combustion : The heat evolved when one mole of a substance is completely burnt at constant volume in excess of oxygen is called it’s heat of combustion.

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