Chapter 2:Chemical Equilibrium
三
2.1:Reversible Reactions
·non-reversible reactions:high activation energy forward and back
↳
eg. diamond to graphite
·
non-reversible reactions:high activation energy forward and low
activation energyback
and water to sodium hydroxide and
↳
eg. salt hydrochloric
acid
·
reversible reactions:low activation forward and back
·non reversible usually exception (mostreversible to some extent
·reversible reaction do finish
not once products are formed
·
closed system (energy can leave orenter but
notmatter)
cause forward and reverse reaction to compete reaction not
complete in either direction
2.2:Evaporation ofWater- A Physical Equilibrium
open system:energy and matter can leave enter system
·
reversible reactions happen in closed systems
only
·
productand reactantmust remain in system
↳ both
dynamic equilibrium rateofcondensation equal to rate of
·
evaporation
·
equilibrium vapour pressure constantvapour pressure
Edynamicequilibrium and
evaporation
equilibrium vapour pressure
gao,
, ↑ vapour pressure favour (products)
vapour phase 三
·
vapour pressure I with temperature
·
strong intermolecular forces in liquid=↓vapour pressure
2.3:Reversible Reaction and Chemical Equilibrium
equilibrium:two opposing reactions happening at the same rate
·
·
double arrows (I show reversible reactions
·
equilibrium causes concentration ofproducts and reactants to be
constant
·
colour, pressure and temperature is also constant
·
forward and back reactions are happening atthe same rate
static appearance at equilibrium
causing
2.4.Equilibrium Position Reactants Vs Products -
·
equilibrium constantconcentrations ofproducts and reactants
relative concentrations productconcentration to reactantconcentration
↳ -
for different systems
is different
equilibrium constant k. numerical value all
of concentrations in a
system
= =
equilibrium
at
a+ bB =c + dD a,b, c and d are
coefficients of
k [C] [D]d
=
substances A, B, C
[A]a[B]b and D
equilibrium constant expression rules:
·
-
only gases and
aqueous appear the expression
in
-
concentrations atequilibrium in molt
-
K has no units
-
K changes as temperature changes
small kvalue favouring reactants
- =
-
large K value favouring products
=
-
k=1 equal
=
concentration
三
2.1:Reversible Reactions
·non-reversible reactions:high activation energy forward and back
↳
eg. diamond to graphite
·
non-reversible reactions:high activation energy forward and low
activation energyback
and water to sodium hydroxide and
↳
eg. salt hydrochloric
acid
·
reversible reactions:low activation forward and back
·non reversible usually exception (mostreversible to some extent
·reversible reaction do finish
not once products are formed
·
closed system (energy can leave orenter but
notmatter)
cause forward and reverse reaction to compete reaction not
complete in either direction
2.2:Evaporation ofWater- A Physical Equilibrium
open system:energy and matter can leave enter system
·
reversible reactions happen in closed systems
only
·
productand reactantmust remain in system
↳ both
dynamic equilibrium rateofcondensation equal to rate of
·
evaporation
·
equilibrium vapour pressure constantvapour pressure
Edynamicequilibrium and
evaporation
equilibrium vapour pressure
gao,
, ↑ vapour pressure favour (products)
vapour phase 三
·
vapour pressure I with temperature
·
strong intermolecular forces in liquid=↓vapour pressure
2.3:Reversible Reaction and Chemical Equilibrium
equilibrium:two opposing reactions happening at the same rate
·
·
double arrows (I show reversible reactions
·
equilibrium causes concentration ofproducts and reactants to be
constant
·
colour, pressure and temperature is also constant
·
forward and back reactions are happening atthe same rate
static appearance at equilibrium
causing
2.4.Equilibrium Position Reactants Vs Products -
·
equilibrium constantconcentrations ofproducts and reactants
relative concentrations productconcentration to reactantconcentration
↳ -
for different systems
is different
equilibrium constant k. numerical value all
of concentrations in a
system
= =
equilibrium
at
a+ bB =c + dD a,b, c and d are
coefficients of
k [C] [D]d
=
substances A, B, C
[A]a[B]b and D
equilibrium constant expression rules:
·
-
only gases and
aqueous appear the expression
in
-
concentrations atequilibrium in molt
-
K has no units
-
K changes as temperature changes
small kvalue favouring reactants
- =
-
large K value favouring products
=
-
k=1 equal
=
concentration
