Kinetics

what is the collision theory

the collision theory states that for a chemical reaction to take place the particles need to collide with each other in the correct orientation and with enough energy

what is activation energy

This is the minimum energy that particles colliding must have in order to produce a successful reactions

what is rate of reaction

change in the amount or concentration of a reactant/ product per unit time 

why do mazwell boltmaz curves begin at (0,0)

zero molecules have zero energy

what is on the y aixis of MB

number of molecules/particles

what is on the x axis of MB

kinetic energy (E)

where is most probable energy shown on curve

peak

mean energy on MB curve

right of most probable energy

how does Ea on curve relate to RoR

molecules with energy equal to or greater than activation energy will collide with enough energy to result in a reaction

the area under the curve of MB relates to

total number of molecules in a sample - doesn’t change with conditions

changing the conditions of a reaction will

change the shape of the curve and therefore the number of molecules with E equal to or greater than Ea

how does temperature effect Rate of reaction

increase in thermal energy leads to an increase in kinetic energy therefore the frequency of collisions will increase and with greater energy increases the chance of E being equal or greater than Ea. Therefore increasing the temperature increases number of successful collisions in a given time

how does increasing the temperature change the MB curve

shifts to the right and lowers therefore greater proportion of molecules have E greater than or equal to Ea

how does decreasing the temperature change the MB curve

shifts to the left and up, less molecules have E greater than or equal to Ea

How does changing concentration/pressure impact RoR

increasing conc. means molecules are packed more closely together, therefore the frequency of collisions will increase as molecules are closer together and more likely to collide with E greater than or equal to Ea therefore increasing number of successful collisions in a given time

what is a catalyst

a substance that increases the rate of reaction by finding alternative energy pathways (with lower Ea) without being used up

how does a catalyst change shape of MB curve

shape unchanged but position of Ea has shifted to the right so greater proportion of molecules have E greater than or equal to Ea, therefore increase number of successful collisions in a given time