CHEM 2 general definitions Flashcards
enthalpy change
the heat energy change of a process measured under conditions of constant pressure
+ve
endo
-ve
exo
Hess’ law
in a reaction, the total HEATenergy change is independent of the route taken from reactants to product
standard enthalpy change
the heat energy change that occurs under standard conditions of temperature and pressure, 298 K, 100KPa
standard enthalpy of formation
enthalpy change which occurs when ONE MOLE of COMPOUND is formed from its ELEMENTS, in their STANDARD STATES at 298 and 100 kpa
standard enthalpy of combustion
the enthalpy change which occurs when one mole of the substance undergoes compete combustion, in excess oxygen, at 298 K and 100kpa
rates of reaction
change in concentration of product/ reactant per unit time
activation energy
the minimum energy a particle needs to cause reaction on collision.
mean bond enthalpy
the average amount of heat energy needed to break a covalent bond across a range of different molecules with that bond.
how to calculate mean bond enthalpy
enthalpy change= energy of bond broken- energy of bonds made
why is 2-bromopropane the major product in the reaction
because it is formed via a secondary carbcation which is more stable than a primary carbocation.
polymer
is a long chain of monomers
monomer
a single molecule that combines with many other monomers to form a polymer
addition polymerisation
two molecules joined but water isn’t formed
