Studied by 6 people
is there loss of net kinetic energy with collisions?
no
what happens when the volume of a gas’s space decreases
pressure increases, increasing number of collisions
what happens when the temperature of a gas increases in an enclosed space?
the average kinetic energy increases, causing increased collision and increased pressure
What are assumptions we make in the ideal gas laws?
the volume of gas particles itself are negligible
there are no intermolecular forces
what is the relationship between pressure and volume
they are inversely proportional
what is the relationship between volume and temperature
they are proportional: increasing temperature will increase volume consistently
what is the relationship between temperature and pressure
as temperature increases, pressure increases proportionally
what is the molar volume?
the volume 1 mole of gases takes up. For all gases at STP, this is 22.7 mol/dm³
which equation can you use when pressure, temperature or volume changes?
(P1 x V1) / T1 = (P2 x V2) / T2
how do you calculate number of moles (n) with pressure (P), volume (V) and temperature (T)
The ideal gas law
n x R = (P x V) / T
R is the universal gas constant, this is in the formula booklet
how do you calculate density?
mass / volume
what are exceptions to the ideal gas law? (PV = nRT)
if the volume of gas particles is not negligible then PV/nRT > 1
if there are intermolecular forces, then PV / nRT < 1
Define rate of reaction
a chemical change per unit of time
how do you calculate the rate of reaction?
Δ[P] / ΔT or -Δ[R] / ΔT
how do you experimentally find the rate of reaction?
when the product has a color: spectophometry
If heat is produced: calorimetry
if gas is produced: gas syringe
If there is a change in mass: scale
If there is a change in concentration: titration
If there is a change in conductivity: electrolysis
which factors affect the success of collisions?
geometry of collisions
energy of collisions
how does pressure affect the rate of reaction?
increased pressure = increased collisions = increased rate of reaction
how does temperature affect the rate of reaction?
increased temperature = increased kinetic energy = more particles with the necessary activation energy = higher rate of reaction
how does surface area affect the rate of reaction?
increased surface area = increased contact opportunity between solutions = increased collisions = increased rate of reaction
how does concentration impact the rate of reaction?
increased concentration = increased collisions = increased rate of reaction
how do catalysts impact rate of reaction
increased catalysts = increased rate of reaction
define equilibrium
the state in which 2 extremes are balanced (reactants and products or states of matter)
define dynamic equilibrium
this is when the change of state/compound is still occurring but both ways, so concentration stays constant
how can you identify the point of equilibrium graphically?
which way does the reaction lean when [R] > [P]
to the left
which way does the reaction lean when [R] < [P]
to the right
what are the characteristics of the equilibrium in a physical or chemical system?
equilibrium is dynamic
equilibrium is achieved in a closed system
the concentration of reactants and products remain constant
there is no change in observable properties
equilibrium can be achieved from either direction (forward or backward)
what is the equilibrium constant?
the ratio between R and P at equilibrium
symbol: K
what is the calculation for K (equilibrium constant)
aA + bB → cC + dD
K = ([C]c x [D]d) / ([A]a x [B]b)
what will the equilibrium constant be for the backwards reaction?
K will be the inverse
define le Chatelier’s principle
when something in a system changes, the solution will react with an opposite reaction
what will happen to the dynamic equilibrium when concentration changes?
when more reactants are added, the rate of the forward reaction increases to go back to the original K
what happens to the dynamic equilibrium when pressure increases?
the reaction with favour the side with less moles/molecules to decrease pressure
what will happen to the dynamic equilibrium when temperature changes?
when temperature decreases, the exothermic reaction will be favoured. This will change K
how do catalysts affect the dynamic equilibrium?
it will not change K or the yield, it will just increase/decrease the rate of the forwards and backwards reaction
which variable will change K?
temperature
how can chemists use knowledge of the equilibrium constant to optimise their goal?
optimising conditions to get a reaction with the highest products
recycling unreacted products
under which conditions do real gases deviate from ideal gas behaviour?
low temperature
high pressure
Note
Flashcard