rates of reactions Flashcards
factors affecting reaction rates
surface area of reactants
concentration of reactants
pressure of gas
temperature of system
catalysts
rate of reaction
defined as change in concentration of reactants/products over a period of time
amount of substance being used/produced over time
collision theory
for a collision to lead to a reaction, reactants must
- collide with each other
- collide with each other with enough energy to break the bonds within the reactants
- collide with the correct orientation to break bonds and form the bonds
a reaction occurs when all of these conditions are met
activation energy
minimum amount of energy to get. reaction going is called activation energy
if the energy of the collision is equal or greater than activation energy then reaction occurs
transition stage
when activation energy is absorbed, a new arrangement of atoms occur
its the state where reactants have highest potential energy
bond breaking and formation happen at this stage
size of activation energy
rate of reaction is dependant on activation energy
orientation of the collisions is also important for reaction rate.
two ways that can increase rate of reaction
inrease number of collision
increase number of collision with an energy that is equal to or greater than activation energy
affect on concentration
increaseing concentration, increases number of particles present, more collision, more successful collisions, increasing reaction rate
for a reaction in gaseous phase, you can increase pressure
affecting on surface area
increasing surface area, incrases number of collision as more particles are exposed meaning reaction rate increase
affect on temperature in reaction
as temperature increase, particles are have more kinetic energy, more collisions occur, therefore higher reaction rate
types of catalysts
homogenous - same physical states as teh reactants and products
heterogenous - different physical states as reactants and products
catalyst
a substance that increases rate of reaction but is not consumed during the reaction
many transition metals and their compounds have strong catalytic effects
catalyst affect on reaction rate
able to make a reaction faster by providing an alternate reaction pathway that has lower activation energy
lower activation energy means that there are more particles that have sufficient energy to react
enzymes
enzymes are biological catalysts made of proteins
enzymes can produce faster reaction rates
enzymes are more selective, catalyse only one specific
they work forming an enzyme- substrate complex
catalytic converters
they are in car exhausts and are designed to remove pollutants gases such as carbon monoxide and nitrogen oxides from engine by converting them into non toxic gases.
gaseous reactants pass through honeycomb structure, coated in particles of metals like Platnum, palladium rhodium
- catalysed reaction takes place on the surface
