Reaction Rates And Equilibrium Flashcards
How do you calculate rate of reaction?
Change in concentration over time
What are the units for rate of reaction?
Moldm-3s-1
What changes can be used to calculate rate of reaction?
Colour change
Mass lost/ gained
PH change
Volume of gas produced
Describe collision theory
Particles must collide with enough energy to break bonds
Particles must collide with correct orientation
To have a successful collision
What factors affect ror?
Temperature Surface area Concentration of reactants (liquid) Pressure (gas) Catalyst
How does temperature affect ror?
More frequent collisions do to faster movement
Collide with more energy
More succeful collisions
How does surface area affect ror?
More exposed reactant
How does pressure affect ror?
More particles per volume
More frequent collisions
How does concentration affect ror?
More particles per volume
More frequent collisions
How do catalysts affect ror?
Provide alternative reaction pathway with a lower activation energy
More collisions are successful
How to Catalysts catalyse a reaction?
Provide surface For reaction to occur on
Form intermediate with reactants
What is a homogeneous Catalyst?
Catalyst and reactants in same physical state
How do homogeneous catalysts catalyse a reaction?
Form an intermediate and are then regenerated forming products
What is a heterogeneous catalyst?
Catalyst and reactants are in different physical states
How do heterogeneous catalysts work?
Reactants are adsorbed onto surface of catalyst (weak bond form)
Bonds within reactants weaken and break
New bonds form between reactants
Products are desorbed as weak bonds break
Give examples of heterogeneous catalyst processes
Haber process
Hydrogenation of alkenes
How to the use of catalysts link to sustainability and economic gain?
Less energy needed
Less electricity
Less fossil fuels burned (to heat and produce electricity)
Less pollution
Lower cost
What is catalyst poisoning?
When impurities bind to catalyst taking up space preventing adsorbtion of reactants
Give examples of catalyst poisoners
Impurities such as sulphur and lead
Describe key points of boltzman distribution curve
No molecules have no energy
No maximum energy
Area=total number of molecules
X-axis= energy
Y-axis = number of molecules
Describe the effect of a higher temp on boltzman distribution curve
Peak shifted down to right
Average energy higher but less molecules have it
Describe the effect of a lower temp on boltzman distribution curve
Peak shifted up to left
More molecules have lower energy
Describe the effect of a catalyst on boltzman distribution curve
Lowers activation energy
More molecules have energy > activation energy
Describe dynamic equilibrium
Rate of forward and reverse reaction are equal
Concentration of reactant and products are constant
Closed system
