3.2.2

Simple Collision Theory

(a)→collision theory: for a chem reaction to take place the particles need to collide with each other with enough energy [Ea] and correct orientation

→more sucessful collisons: higher rate of reaction

→more concentrated a solution: more particles in given vol; increased collision frequency: higher rate of reaction

→more increased pressure: less vol space for particles to move in; increased collision frequency; higher rate of reaction

(b)→rate of reaction: speed at which a chem reaction takes place [image of calculation]

→rate throughout reaction: reactants are used up and changed into products; so as reaction proceeds the conc of reactants is decreasing as conc of products increase; so rate of reaction is not the same throughout and changes

→calculating rate of reactions with conc-time graph: when taking product measurments the temp must be constant as it can change rate of reaction [image]

Catalysts

(c)(i)→catalyst: a substance that increases reaction rate without w being used up by overall reaction

(ii)→how catalysts work: provides alternative pathway with lower activation energy [image reaction profile]

(d)(i)→homogeneous catalyst: catalyst same phase [state] as reactants

→heterogeneous catalyst: catalyst different phase as reactants

(ii)→benefits of catalysts: overwiegh toxity of sum catalysts

  • speeds reaction rate so lower temp and pressures used

  • saves energy cost as less needed to provide these conditions

  • also fewer co2 emmisions from burning fossil fuels to get this energy

The Boltzmann distribution

(f)→Maxwell-Boltzmann distribution curve: shows distribution of energies and the activation energy [image]; only certain number of molecules have enough or more energy than activation energy, causing sucessful collision s

(g)(i)→temp changes: image

  • increased temp; particles gain more kinetic energy

  • so have = or more energy to Ea

  • move around faster so more frequent successful collissions

  • faster rate of reaction

(ii)→catalysts: image

  • provides reactants alt pathway; lowers activation enegy

  • more particles + or more energy than Ea

  • so more frequent successful collisions

  • faster rate of reaction