Enthalpy Flashcards
What is Enthalpy?
The heat energy stored in a chemical system.
What symbol is used to represent Enthalpy?
H
Define the term Exothermic using key points.
Exothermic Reactions are reactions where energy is given out to its surroundings and the temperature increases.
The Enthalpy (Delta H) is negative.
The products have less energy than the reactants.
Define the term Endothermic using key points.
Endothermic Reactions are reactions where energy is taken in from its surroundings and the temperature decreases. The Enthalpy (Delta H) is positive The products have more energy than the reactants.
What reaction causes the temperature of the surrounding to drop is
Endothermic
Name the standard conditions
100kPa, 298K and 1mol/dm³
What is the equation for enthalpy change?
Enthalpy Change = Enthalpy Products - Enthalpy Reactants
What is activation energy.
Minimum amount of energy needed to start a reaction.
What is the enthalpy change of formation?
The enthalpy change that takes place when one mole of a compound is formed from its elements in their standard states under standard conditions
What is the enthalpy change of a reation?
The enthalpy change that accompanies a reaction in the molar quantities shown in a chemical reaction under standard conditions with all reactants and products in their standard states
What is the enthalpy change of combustion?
The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions (with all reactants and products in standard states)
What is the enthalpy change of nuetralisation?
The enthalpy change that accompanies the reaction of an acid by a base to form one mole of H2O under standard conditions
Give an example equation of the enthalpy of combustion.
C₄H₁₀ (g) + 6.5 O₂ (g) → 4 CO₂ (g) + 5 H₂O (l)
Give an example equation of the enthalpy of formation.
E.g 2C(s) + 2H₂(g) —> C₂H₄ (g)
