Factors effecting reaction rate Flashcards
what does collision theory explain
how reactions occur and why they occur at different rates
what must happen for chemical reactions to happen
particle collision must occur
what is the activation energy
The activation energy is the minimum energy with which particles must collide in order to cause a chemical reaction.
what are the four main factors affecting reaction rates
1) Temperature
2) Concentration
3) Pressure
4) Surface area
5) Catalysts
what does increasing the concentration of dissolved reactants do
increasing the concentration of dissolved reactants increase the number of particle collisions
what does increasing the pressure of the gas reactants do
Increasing pressure is like increasing the concentration.
It increases the frequency (number) of collisions. This increases the rate of reaction (makes the reaction faster).
what does increasing the temperature do
Increasing the temperature increases the frequency (number) of collisions.
Increasing the temperature increases the energy of reactant particles. This means that a greater proportion (more) of the particles will have more energy than the activation energy that is needed.
Together, these lead to more successful collisions. This increases the rate of reaction.
what does increasing the surface are of the solid reactants do
Increasing the surface area increases the frequency (number) of collisions. This increases the rate of reaction.
This is often done by breaking up solids into smaller lumps (e.g. powders).
This increase in surface area to volume ratio makes sure that more particles are exposed to attack.
what does a catalyst do
catalysts speed up chemical reactions and cannot be used up during the process
what are the properties of reactants
1) Surface area of solid reactants
2) Concentration of dissolved reactants
3) Pressure of gas reactants
how do catalysts increase the rate of chemical reactions
catalysts increase the rate of chemical reactions by lowering the activation energy by providing a different reaction pathway
what does catalysts not being used up in reactions mean
1) it can be re-used indefinitely
2) they are not found in chemical equations
what will catalysts often need after being used
1) Catalysts will often need a clean after usage
2) Catalysts may require regeneration
what are enzymes and where can they be found
enzymes are biological catalysts which can be found in yeast to produce alcohol
what do catalysts often come as and why
catalysts often come as powders, pellets or fine gauzes as these substances have a high surface area
