Studied by 7 people
Collision Theory
reactants need to combine w/ enough energy and in proper orientation in order to react
effective collision
a collision that results in a chemical reaction
law of conservation of energy
energy cannot be created or destroyed
kinetic energy
energy used for motion
potential energy
stored energy- when reactants collide
activated complex
unstable phase while reaction is occurring
enthalpy
the amount of energy(heat) being stored in bonds of a compound.
Note: products & reactants almost always have an absorption release of enthalpies
endothermic reaction
when products have a higher enthalpy
reaction in which energy is absorbed
exothermic reaction
reaction in which energy is released
when products have a lower enthalpy
specific heat
substance ability to resist temperature change
high specific heat
requires a lot of energy to inc. or dec. in temperature
Calorimetry Equation
mcΔT
Q
heat (joules)
M
mass (grams) *if not in grams, convert
C
specific heat (j/gC)
T
temperature (C)
reactants
1
products
6
activation complex
3
Heat of the reaction
5
Q of absorbed
Q of released =
Q of released
Q of absorbed =
-Q
if energy is lost (__Q)
+Q
if energy is absorbed (__Q)
ΔH (delta H)
change in variable
H final-H initial
-ΔH
exothermic H
+ΔH
endothermic H
potential energy (hold together)
there is a specific amount of energy holding together H2 & O2
potential energy
When the particles collide, Kinetic Energy becomes ______
5 things to increase rate of Effective collision
temperature (changes energy & likelihood, speed & rate)
pressure (decrease in volume, more collisions)
surface area (increase # of particles for collisions)
presence of catalyst
concentration (likelihood of collisions is higher bc more molecules)
no, sometimes they bounce off because:
not enough energy
did not collide in the right spot
Do molecules always react when they collide?
they collide
why do molecules react?
entropy
the amount of disorder in a system
naturally increases (easier to create disorder than order)
least entropy
particles in solids stay in place: rigid, fixed shape, fixed volume (____entropy)
most entropy
gas particles move freely & randomly (____ entropy)
least particles
least disorder (solid)
most particles
most disorder (gas)
S
entropy
entropy equation
ΔS = S final - S initial
spontaneous
uses energy to create reaction
once reaction starts, continues on own
these reactions can possibly take a long time
non spontaneous
needs a constant source of energy
-ΔG
spontaneous reaction
which thermic is more favorable
exothermic (more spontaneous)
which ΔS is more energetically favorable
+ΔS
+ΔS
inc. in entropy
-ΔS
dec. entropy
Exothermic + inc entropy (-ΔS) =
ALWAYS SPONTANEOUS
Endothermic + dec. entropy =
NEVER SPONTANEOUS
gibbs free energy equation
ΔG = ΔH - TΔS
Note 
Flashcard (93)