Enthalpy Flashcards
What is the enthalpy change of a reaction?
The heat change in a reaction at constant pressure
What are the standard conditions for enthalpy?
100KPa pressure
298K (25 degrees Celsius)
What is an endothermic reaction?
Reactions that absorb heat energy from the surroundings
Endothermic reactions: products and reactants?
Products are higher in energy than reactants
Delta H is positive
What is an exothermic reaction?
A reaction that releases energy to the surroundings
Exothermic reactions: products and reactants?
Products are lower in energy than reactants
Delta H is negative
What is delta r H?
Standard enthalpy change of reaction
The enthalpy change of a reaction according to the molar quantities in the equation under standard conditions
What is delta neut H?
The standard enthalpy change of neutralisation
The enthalpy change when an acid and alkali react to form 1 mole of water under standard condtions
What is delta c H?
Standard enthalpy change of combustion
The enthalpy change when 1 mole of a substance is completely burned in oxygen to make CO2 and H2O under standard conditions
What is delta f H?
Standard enthalpy change of formation
The enthalpy change when 1 mole of a compound is formed from its elements in their standard states under standard conditions
What needs to happen to energy in order to break a bond/?
To break a bond- energy needs to be absorbed
Is bond breaking endothermic or exothermic?
Endothermic process- delta H is positive
What happens when bonds are formed: exothermic?
Energy is released
Exothermic reactions?
Bonds are made
Delta H is negative
What is the formula for enthalpy change?
Total energy to break bonds - total energy released forming bonds
