4.3 Collision theory Flashcards
factors affecting rate
surface area
concentration
temperature
catalyst
surface area
more solid is exposed to other particles
more frequent collisions per unit time
more successful collisions per unit time
concentration
more particles per unit volume
more frequent collisions per unit time
more successful collisions per unit time
temperature
particles have more kinetic energy
more frequent collisions with enough energy per unit time
more successful collisions per unit time
catalyst
provide an alternative route with a lower activation energy
more collisions have enough energy to react
more frequent collisions per unit time
more successful collisions per unit time
how to increase concentration
dissolve more solute particles
how to increase pressure
make the reaction vessel smaller
effect of concentration experiment
disappearing cross experiment
method: react sodium thiosulphate solution with hydrochloric acid - keep mixing until you can no longer see the cross - record the time taken for the cross to disappear
result: rate and concentration are proportional
control variables: total volume of solution, concentration of HCl, temperature
effect of surface area experiment
marble chip experiment
method: react calcium carbonate (marble) chips with hydrochloric acid
results: graph plotted with the higher surface area and the original surface area
higher SA has a steeper start - rate increases so volume CO2 is increasing faster
same final volume- total amounts of reactants hasn’t changed - eventually produces same amount of CO2
control variables: mass marble chips, volume of HCl, temperature
how to increase surface area
cutting or grinding up the solid
effect of temperature experiment
react magnesium with HCl
magnesium disappears
measure time taken for magnesium to disappear and record the temperature of the HCl
control: mass and SA of Mg, volume of HCl
results: not a straight line
how to increase temperature
heating
rate equation
1/time taken
effect of catalysts experiment
hydrogen peroxide experiment
catalysed by manganese oxide
input: which catalyst is being used
output: volume of O2
control: volume and concentration of H2O2, temperature, mass/SA of catalyst
results: more effective catalysts increase rate more efficiently (steeper line)
What is activation energy
The amount of energy particles need to react
