Enthalpy Flashcards
(13 cards)
What is Enthalpy?
Enthalpy (H) is a measure of energy content of a system.
What is the unit for Enthalpy change?
Kjmol-1
If the reaction is endothermic is the Enthalpy change positive or negative?
Positive
If the reaction is exothermic is the Enthalpy change positive or negative?
Negative
In an exothermic does the energy rise or fall?
The temperature rises
In an endothermic reaction does the temperature rise or fall?
The temperature would fall
What are the standard conditions?
Pressure- 1 atmosphere (100 kPa)
Temperature-25 (unless stated otherwise)
What is the Enthalpy change of reaction?
The Enthalpy change of reaction is the Enthalpy change when the number of moles shown in the equation react to form the product.
What is the standard enthalpy of reaction?
When it is under standard conditions with all the substances in their standard states.
What is the Enthalpy change of combustion?
The Enthalpy change of combustion is the Enthalpy change when 1 mole of a substance is burned completely in oxygen
What does “burning completely” mean?
That all the carbon in the compound is converted into carbon dioxide
The Enthalpy change of combustion must refer to a reaction in which….
1 mole of the compound is burned.
What is the Enthalpy change of formation
the Enthalpy Change of formation of a substance is the enthalpy change when one mole of a substance is formed from its elements
