Chemical Reactions & Equilibrium Flashcards
Describe the criteria for a successful collision
-reactant molecules must collide with each other
-reactant molecule must collide with sufficient energy to break the bonds within the reactants
-reactant molecules must collide with the correct orientation to break the bonds within the reactants
define rate of reaction
the change in concentration of the reactants or products per unit time
How does increased surface area influence rate of reaction
increase surfaced area
increased frequency of successful collisions per unit time
increased rate of reaction
How does increased concentration influence rate of reaction
increase concentration
increase number of particles in a given volume
increase frequency of successful collisions per unit time
increased rate of reaction
how do you increase pressure
decrease the volume of the system
how do you decrease pressure
increase the volume of the system
How does increased pressure inference rate of reaction
increase pressure
increase concentration of particles
increase frequency of successful collisions per unit time
increased rate of reaction
How does increased temperature influence rate of reaction
increase temperature
increased average kinetic energy
increased proportion of particles with energy greater than or equal to the activation energy
increased frequency of successful collisions per unit time
increased rate of reaction
Two types of catalysts
homogenous and heterogenous
How do catalysts increase rate of ration
provide an alternative reaction pathway by lowering activation energy and in turn increasing the proportion of particles with energy equal to or above the activation energy.
increasing the frequency of successful collisions per unit time and increasing rate of reaction
define equilibrium
when the forward and back reactions occur at the same rate, the reaction is said to be at equilibrium
Identify conditions at equilibrium
-amount of mol of substance is constant
-concentration of substances is constant
-pressure constant (gas system)
-temperature constant
purpose of Kc value
it shows the extent of the reaction
how to calculate Kc value
concentration of product(s) to power of coefficient / concentration of reactant(s) to power of coefficients
what impacts Kc
temperature ONLY
How to get units of Kc
coefficients of product / coefficients of reactant (simplify)
If Kc is greater than 10^4 then
reaction goes to completion (negligible amount of reactant left)
If Kc is less than 10^-4 then
reaction occurs to a negligible extent (negligible amount of product formed)
Kc values between 10^-4 and 10^4 are
indicative of the forward and back reactions occurring to a moderate extent
Find K2 for the reverse reaction of K
1/K
Find K2 for the coefficients of reaction K being doubled
K^2
Find K2 for the coefficients of reaction K being halved
K^1/2
How is Kc influenced in EXOTHERMIC reaction
increase in temperature decreases K
decrease in temperature increases K
How is Kc influenced in ENDOTHERMIC reaction
increase in temperature increase K
decrease in temperature decreases K
What is Q (reaction coefficient)
same calculation as K but not necessarily at equilibrium
How are Q and Kc related to equilibrium
if Kc<q>Q then the system will shift right to achieve equilibrium and more products will form
if Kc = Q then the system is at equilibrium</q>
ICEFC stands for
initial mol
change in mol
number of mol at equilibrium
Final CONCENTRATION
Key principal of Le Chatelier’s
if an equilibrium system is subjected to change then the system will shift in a direction that PARTIALLY OPPOSES that change
How does temperature influence equilibrium yield
An increase in temperature will be partially opposed by favouring the energy absorbing endothermic reaction
A decrease in temperature will be partially opposed by favouring the energy releasing exothermic reaction
How do catalysts influence equilibrium yield
NO change as they effect the rate of the forwards and reverse reactions to an equal extent
How does the addition of an inert gas influence equilibrium yield
has no effect on the position of equilibrium, provided the volume of the container remains constant
Name 3 inert gases
He
Ne
Ar
How does the addition of a reactant or product influence equilibrium
addition of a product or reactant increases the concentration of that reactant or product and hence the reaction that uses up that reactant or product will be promoted to partially opposes the increase in concentration of the reactant or product and hence decrease the concentration of that reactant or product
How does removal of a reactant or product influence equilibrium
removal of a product or reactant decreases the concentration of that reactant or product and hence the reaction that produces that reactant or product will be promoted to partially opposes the decreases in concentration of the reactant or product and hence increase the concentration of that reactant or product
How does dilution impact equilibrium
a dilution decreases the concentration of all the reactants and products and is partially opposed by favouring the reaction that produces more mol of solution
How does volume influence pressure
increase volume decreases pressure & decrease volume increases pressure
How does pressure impact equilibrium
increase in pressure is partially opposed by promoting the reaction that produces fewer mole of gas
decrease in pressure is aerially opposed by favouring the reaction that produces more mole of gas
Write the two chemical reactions for CO poisoning
Hb4 + 4O2 –> Hb4O8. -K1
Hb4 + 4CO –> Hb4(CO)4. -K2
Why is CO poisoning dangerous
Because K2 is much greater than K1 then even at very low concentrations haemoglobin in the blood and CO bind to form the complex - Hb4(CO)4
Why would high concentrations of oxygen be delivered for CO poisoning
By pumping in oxygen, this increases the oxygen concentration and favours the forward reaction to produce Hb4O8. This reduces the amount of Hb4 in the blood and as a result the second reaction will shift left to partially opposes the decrease in Hb4 concentration and produce more Hb4. Less Hb(CO)4 complexes form and CO poisoning is minimised
why does addition of inert gas have have no effect on ror
inert gas particles are not apart of the reaction and hence do not affect the number of collisions and successful collisions per unit time.
