kinetics Flashcards
when can reactions occur
when collisions take place between particle’s having sufficient energy, called activation energy
why do most collisions not lead to a reactions
particles have less than activation energy
what is the maxwell-boltzmanmn distribution
distribution of molecular energies in gases
what is the vertical line through the peak of maxwell boltzmann
most probable energy
what is the vertical line after the peak of maxwell boltzmann
mean energy
why does the maxwell botxmann start at the orgin
zero moleucles have zero energy
changing reaction conditions causes what alterations to maxwell botzmann
alter the shape of the curve so that the number of particles with energy greater than activation energy is different, total area under curve will remain same as represents total number of molecules in the sample
rate of reaction meaning
qualitative effect of temperutre changes on rate of reaction
when a substance is heated thermal energy is transferred to it which is converted to kinetic energy, increased movement of molecules means more frequent successful collisions as have more particles have greater energy than activation energy, so increases the rate of reaction
use the maxwell-boltzmann distribution to explain why a small temperature increases can lead to a large increases in rate
at increased temp it the maxwell-boltzmann distribution shifts to the right so a greater proportion of molecules have energy greater than or equal to acivation energy
qualative effect of changes in concentration on rate of reaction
increased concentration, more molecules of substance occur in the same volume meaning they are packed closer toghether, therefore collisions between molecules become more likely and the chances of a collision occuring with erngy greater than activation energy increases, rate of reaction increases
qualtive effect of a change in pressure of a gas on rate of reaction
increased concentration molecules of substance occur in the smaller volume meaning they are packed closer toghether, therefore collisions between molecules become more likely and the chances of a collision occuring with erngy greater than activation energy increases, rate of reaction increases
what is a catalyst
a substance that increases the rate of chemical reaction without being changed in chemical composition or amount
how does a catalyst work
by providing an alternative reaction route of lower activation energy
use maxwell boltzmann distribution to explain how a catalyst increases the rate of a reaction involving a gas
maxwell boltzmann distribution curve is unchanged in shape but the posistion of the activation energy is shifted to the left so that a greater proportion of molecules have suffiecient energies to react
