Enthalpy Flashcards
What is the law of conservation of energy?
Energy cannot be created or destroyed
What happens to the heat energy in a chemical reaction involving an enthalpy change?
Transferred between system and surroundings
What two things can energy transfer be?
Exothermic
Endothermic
What does exothermic mean?
Heat lost to surroundings from system
What does it mean if it’s endothermic?
System gains energy from surroundings
A
When is the enthalpy change negative?
When it’s Exothermic
What is enthalpy?
Measure of the heat energy in a chemical system
What is the activation energy?
The energy input required to break bonds
Minimum energy required for a reaction to happen
What are standard conditions?
1 atm pressure (100kPa)
298k temp
1 moldm-3 conc (only for concentrations )
Standard state of substance
What is the standard enthalpy change of reaction?
The enthalpy change that accompanies a reaction in the molar quantities shown in an equation under standard conditions
What is the standard enthalpy change of formation?
The enthalpy change that takes place when one mole of a compound is formed from its elements under standard conditions
What is the standard enthalpy change of combustion?
The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions
What is the enthalpy change of neutralisation?
The energy change that accompanies the reaction of an acid by a base to form one mole of water under standard conditions
What is the specific heat capacity?
The energy required to raise the temperature of one gram of a substance by one k
What is the equation for calculating an energy change?
q=mc^T
