Enthalpy Changes Flashcards
What delta H value is exothermic reactions?
Negative because more energy is released when bonds are formed in the products than was needed to break bonds in reactants
What is the definition of enthalpy of combustion?
The enthalpy change when 1 mole of the substance is completely burned in excess oxygen
What is the definition of activation energy?
Minimum energy required to start a reaction by breaking bonds
What type of reaction is combustion always?
Exothermic m
What does Hess’ law state?
For a given chemical reaction the energy change is the same irrespective of the route taken provided the initial and final conditions are the same
What is the definition of enthalpy of formation?
The enthalpy change when one mole of a substance is formed from its element in their standard states
What is the definition of endothermic?
A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants resulting in energy being taken in
What types of reactions are endothermic?
Any change in state
What is the definition of exothermic reaction?
A reaction in which the enthalpy of products is smaller than the enthalpy of the reactants resulting in heat lost to surroundings
What is the definition of enthalpy of reaction?
The enthalpy change for s reaction in the molar quantities expressed in the equation
What delta value is endothermic reactions?
Positive because less energy is released when bonds are formed in the products than was needed to break bonds in reactants
What is the definition of enthalpy?
The heat content stored in a chemical system
What is the definition of enthalpy of neutralisation?
The enthalpy change when one mole of water is formed from neutralisation of an acid and an alkali
