Transcript Ch 19.1 Notes

Chapter 19 Section 1
Rates of Reaction
rate- measures the speed of any change that
occurs within an interval of time
rate = change/time
-rates of chemical reactions can vary greatly
ex- lighting a match vs. producing coal
-Some reactions cannot be reversed
ex- bike left outside to rust
collision theory- atoms, ions and molecules can
react to form products when they collide
provided they have enough kinetic energy
-particles without enough kinetic energy will
bounce apart when they collide producing no
reaction
-bonds holding molecules together can also
break apart
activation energy- the minimum amount of
energy that particles must have in order to
react
activated complex- the arrangement of atoms at
the peak of the activation energy barrier
-this is right before reactants go to productvery unstable
*page 535
*called transition state- unstable intermediate
structure that connects reactants to products
-it is just as likely to form back to reactants as it
is to form products
Factors Affecting Reaction Rates
1) Temperature
-speeds up rate of reaction as temp increases
-higher temp = more collisions
2) Concentration
-increasing the # of particles will speed up
rate
-more particles = more collisions
3) Particle Size
-decrease particle size increases rate
-larger surface area = faster rate
4) Catalysts
-a substance that speeds up a reactions
without being used up
enzymes- catalysts used in body processes
inhibitor- substance that interferes with the
action of a catalyst