rates and equilibrium Flashcards
collision theory
reactant particles must collide for chemical reaction to occur w/ correct orientation and sufficient energy
define activation energy
the minimum amount of energy required for a reaction to take place
effect of changing concentration on equilibrium
increasing conc of reactant or product will favour reaction where substance is reactant, so removing substance
if substance = removed, equil. will shift in order to replace it
adding or removing solids/liquids will X change equ = must cgange CONC
describe la chatelier’s principle
a system in equilibrium has the tendency to partially oppose any disruption to re-establish equilibrium and minimise effects of changes
define rate of reaction
the change in concentration of a reactant or product per unit time
effect of using catalysts on RR
-reduce AE of reaction as reactant particles on catalyst surface disrupt bonds w/in molecule -> different chemical pathway
-increases proportions of particles w sufficient energy
-increase frequency of successful collision
-increase ROR
effect of changing temp of reactants on ROR
-increase temp = increase kinetic energy of reactant particles
-increase proportion of particles w sufficient energy
-increase frequency of successful collisions
-increase ROR
effect of changing pressure of reactant gases on ROR
-decrease volume = increase pressure
-increase volume = decrease pressure
-increase number of particles per unit volume if volume dec + pressure incr
-increase frequency of collision
-increase freq. of successful
-increase ROR
effect of surface area of solid reactants on ROR
-increase surface area = increased no. of particles that are exposed and available for collision
-increase frequency of collisions
-increase frequency of successful collisions
-increase ROR
effect of changing concentration of solution on ROR
-increase conc of solution
-increase no. of particles per unit volume
-increase frequency of collisions
-increase frequency of successful collisions
terminology for equilibrium
forward reaction is favoured = equilibrium is shifted to the right
reverse reaction is favoured = equilibrium is shifted to the left
what is dynamic equilibrium
-when the rate of the fwd reaction equals the rate of the rev reaction - both processes are occurring simultaneously
-no observable change
-concentration of products and reactants remain constant but x always equal
is dynamic equilibrium a closed or open system?
closed system to prevent reactant or products from escaping or being introduced
effect of changing pressure on equilibrium
increase pressure = always favours reaction that produces fewer moles of gas
decrease pressure = favours reaction that produces more moles of gas
effect of changing temp on equilibrium
increase temp = favour endothermic reaction, where enthalpy change = POS
decrease temp = favour exothermic reaction, where enthalpy change = NEG
effect of adding catalyst on equilibrium
increase rate of both forward and reverse reactions - equilibrium may be reached more quickly, but not favour one or change position of equilibrium
define haber process
the industrial process of the manufacture of ammonia from hydrogen and nitrogen
compromise positions of the haber process
-at 200 atm, lower pressure than preferred b/c higher pressure = increased energy costs + more exp. equip to maintain high pressure
-400-450 deg celcius, lower temp favours exo reaction but too slow of ROR and decrease eq. yield (maximise yield per day, not cycle)
-uses iron catalyst
