Energetics Flashcards
What is enthalpy change?
The change in heat energy under constant pressure.
What are standard conditions?
- 100Kpa
- 298K
- 1.00 mol dm-3
Why does the temperature increase in exothermic reactions?
Why does the temperature decrease in endothermic reactions?
Why is the enthalpy change in an exothermic reaction negative?
Why is the enthalpy change in an endothermic reaction positive?
What are mean bond enthalpies?
The amount of energy needed to break one mole of covalent bonds.
Why do we use a mean when considering bond enthalpies?
The same bond will have a different bond enthalpy over a range of different compounds so we use a mean.
How do we measure an enthalpy change in a reaction?
calorimetry
q= mcT
H=q/n
What is the equation for measuring an enthalpy change?
What is the standard enthalpy of formation?
The enthalpy changes when one mole of a compound is formed from its constituent elements and all substances are in their standard states.
What is the enthalpy of combustion?
The enthalpy change when one mole of a substance is completely burned in oxygen and all substances are in their standard states.
What is the enthalpy of neutralization?
The enthalpy changes when one mole of water is formed from the reaction of an acid and alkali.
What is the enthalpy of solution?
The enthalpy changes when one mole of an ionic compound is dissolved in a large enough amount of water that the ions no longer interact.
What is the hydration enthalpy?
The enthalpy change when one mole of gaseous ions becomes one mole of aqueous ions.
What is the enthalpy of atomization?
The enthalpy changes when one mole of gaseous atoms are formed from elements in their standard states.
What is the first ionization energy?
What is the second ionisation energy?
What is the first electron affinity?
What is the second electron affinity?
What is the enthalpy of lattice formation?
The enthalpy changes when one mole of an ionic compound is formed from its gaseous ions.
What is the enthalpy of lattice dissociation?
The enthalpy changes when one mole of an ionic compound is broken down into its gaseous ions.
What is Hess’ Law?
The enthalpy change is independent of the route taken.
What is Hess’ Law for the enthalpy of formation?
What is Hess’ Law for the enthalpy of combun
stion?
What is Hess’ Law for the enthalpy of solution?
enthalpy of dissociation + hydration enthalpy.
