Enthalpy & Enthalpy Change Flashcards
What is enthalpy?
A measure of heat energy in a chemical system
What does the law of conservation of energy state?
Energy cannot be created or destroyed
What is an exothermic reaction? What is its enthalpy sign?
A reaction which releases energy -
Enthalpy change is negative
What is an endothermic reaction? What is its enthalpy sign?
A reaction which absorbs energy - the enthalpy change is positive
Define enthalpy change of formation
The enthalpy change when one mole of a substance is formed from its constitute elements in their standard States under standard conditions
Define enthalpy change of combustion
The enthalpy change when one mole of a substance is burned completely in excess oxygen in standard conditions
Define standard enthalpy of reaction
The enthalpy change when one mole of a substance is transformed by a chemical reaction in standard conditions
What is an enthalpy profile diagram for endothermic reaction
Reactants start lower than products
What is an enthalpy profile diagram for exothermic reactions?
Reactants start at top, reactants at bottom
State the standard conditions for enthalpy
298K
101Kpa
