Chapter 9 Flashcards
Definition of enthalpy
Enthalpy is The heat content that is stored in a chemical system
Definition of enthalpy change
Enthalpy change is the heat transferred in a reaction at constant pressure
What is an exothermic enthalpy change
And exothermic and enthalpy change is a reaction in which the entropy of the products is smaller than the entropy of the reactants so heat is lost to the surroundings and delta H is negative
What is an endothermic enthalpy change
And endothermic and to be change is a reaction in which the enthalpy of the product is greater than the enthalpy of the reactants so heat is taken in from the surroundings and delta H is positive
Draw an Enthalpy profile diagram for an exothermic and endothermic reaction
In the exothermic reaction the reactants are at higher enthalpy than the products and vice versa for endothermic
What is activation energy
Activation energy is the minimum energy required to start a reaction by the breaking of the bonds
What are standard conditions
Standard conditions are standard pressure which is 100 kPa standard temperature which is 298 Kelvin and standard state the physical state of the substances understand the conditions
Definition of standard enthalpy change of reaction
Standard enthalpy change of reaction is the entropy change that accompanies a reaction in the molar quantities shown in the chemical equation under standard conditions with all reactants and products in standard states
Definition of the standard entropy change of formation
The enthalpy change when one mole of a compound is formed from its elements in their standard states understand the conditions
Definition of the standard entropy change of combustion
The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions with reactants and products in their standard states
Definition of the standard enthalpy change of neutralisation
The end to be change when an acid and alkali react together to form one mole of water understand conditions with all reactants and products in their standard states
What is the equation for heat energy
Q=mc delta T
M is mass
C is specific heat capacity
T is change I’m temperature
What is the equation for enthalpy change
Enthalpy change = q/mol
Why may the calculated value of enthalpy change be different from the data book
Heat could’ve been lost to the surroundings incomplete combustion could’ve taken place or it could’ve been done and the non-standard conditions
What is average bond enthalpy and what are the limitations
Average bond enthalpy of the energy required to break one mole of a specific type of bond in the gassiest molecule however average bond enthalpy is calculated from the actual bond enthalpies different chemical environments so the actual bond enthalpies may differ from the average value
