Enthalpy Of Combustion Flashcards
What is enthalpy of combustion
Measure of chemical energy stored in a substance
What’s IE for enthalpy change
Quantity of heat energy released in a reaction
Most chemical reactions are
Exothermic
What happens if a reaction are exothermic
•Heat energy released
•But if too much heat energy dangerous and needs to be removed
What about endothermic reactions heat energy needs to be supplied, why?
To keep the reaction going once it has starting
The enthalpy combustion of a substance is enthalpy change when?
when one mole of the substance burns completely an oxygen
Enthalpy change units for 1 mole are measured in
Kj mol-1
Enthalpy combustion values are always what
Negative (exo)
And are always quoted 1 mole of the substance being burned
How can enthalpy he used to calculate heat a known mass of water
By burning substance in question
After the water is heated the temperature will do what
Increase (temp of water)
The more carbon atoms in the chain?
The more energy is released when substance is burned
Factors for greater values or less
٠Heat being lost to souroundings
٠Substance being burned in air rather than pure o2= incomplete combustion
•The mad if the substance nah be incorrect some of the substance may have evaporated
Enthalpy of solution
The enthalpy change when 1 mole of substance is completely dissolved in 1L of solution
Enthalpy of solution can be
Exothermic or endothermic
Ex= -VE sign
En= +Ve sign
What is meant by the term exothermic
A reaction where heat is released
When will enthalpy of solution be exothermic
If temperature increases
