Collision Theory - 4th Flashcards
when can a chemical reaction only happen?
- if the reactant particles collide with enough energy
what is activation energy?
- the amount of energy the particles need to react is called activation energy
what will happen to particles which collide with less energy than the activation energy?
- will just rebound and remain unchanged
what does the overall rate of reaction involving millions of particles depend on?
- collision frequency
- percentage success
what is collision frequency?
- how often do the particles collide with each other
what is percentage success?
- what percentage of the collisions have enough energy?
what are four common factors which affect rate of reaction?
- surface area
- concentration
- temperature
- catalysts
why does a higher solid surface area increase the rate of reaction?
- more of the solid is exposed to the other particles
- so the collision frequency is higher
- so there are more successful collision per unit time
why does a higher temperature a increase the rate of reaction?
- the particles have more kinetic energy
- so the percentage of collisions with enough energy is higher
- so there are more successful collisions per unit time
why does a higher solution concentration/gas pressure increase the rate of reaction?
- there are more particles per unit volume
- so the collision frequency is higher
- so there are more successful collisions per unit time
why does a catalyst increase the rate of reaction?
- they provide an alternative route with a lower activation energy
- so the percentage of collisions with enough energy is higher
- so there are more successful collisions per unit time
how can you increase the concentration of a solution/gases?
- by dissolving more solute particles
how can you increase the pressure of a solution/gases?
- by making the reaction vessel smaller
how can the effect of concentration on rate be demonstrated?
- by reacting sodium thiosulphate solution with hydrochloric acid to make sodium chloride, sulphur solid , sulphur dioxide and water
what is the chemical equation for the disappearing cross experiment?
- Na2S2O3 (aq) + 2HCl (aq) -> 2NaCl (aq) + S (s) + SO2 (g) + H20