Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms...
-
Upload
brook-lewis -
Category
Documents
-
view
217 -
download
0
Transcript of Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms...
![Page 1: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/1.jpg)
Reaction Rate
How Fast Does the Reaction Go
![Page 2: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/2.jpg)
Collision Theory In order to react molecules and atoms
must touch each other.They must hit each other hard enough to
react.Anything that increase these things will
make the reaction faster.
![Page 3: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/3.jpg)
Ene
rgy
Reaction coordinate
Reactants
Products
![Page 4: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/4.jpg)
Ene
rgy
Reaction coordinate
Reactants
Products
Activation Energy - Minimum energy to make the reaction happen
![Page 5: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/5.jpg)
Ene
rgy
Reaction coordinate
Reactants
Products
Activated Complex or Transition State
![Page 6: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/6.jpg)
Ene
rgy
Reaction coordinate
Reactants
Products
Overall energy change
![Page 7: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/7.jpg)
Things that Effect RateTemperatureHigher temperature faster particles.More and harder collisions.More concentrated closer together the
molecules.Collide more often
![Page 8: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/8.jpg)
Things that Effect RateParticle sizeMolecules can only collide at the surface.Smaller particles bigger surface area.Smallest possible is molecules or ions.Dissolving speeds up reactions.
![Page 9: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/9.jpg)
Things that Effect RateCatalysts- substances that speed up a
reaction without being used up.(enzyme).Speeds up reaction by giving the reaction a
new path.The new path has a lower activation
energy.More molecules have this energy.The reaction goes faster. Inhibitor- a substance that blocks a
catalyst.
![Page 10: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/10.jpg)
Ene
rgy
Reaction coordinate
Reactants
Products
![Page 11: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/11.jpg)
Pt surface
HH
HH
HH
HH
Hydrogen bonds to surface of metal.
Break H-H bonds
Catalysts
![Page 12: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/12.jpg)
Pt surface
HH
HH
Catalysts
C HH C
HH
![Page 13: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/13.jpg)
Pt surface
HH
HH
Catalysts
C HH C
HH
The double bond breaks and bonds to the catalyst.
![Page 14: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/14.jpg)
Pt surface
HH
HH
Catalysts
C HH C
HH
The hydrogen atoms bond with the carbon
![Page 15: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/15.jpg)
Pt surface
H
Catalysts
C HH C
HH
H HH
![Page 16: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/16.jpg)
Reaction MechanismReaction mechanism is a description of
how the reaction really happens.An intermediate is a product that
immediately gets used in the next reaction.
![Page 17: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/17.jpg)
This reaction takes place in three steps
![Page 18: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/18.jpg)
Ea
First step is fast
Low activation energy
![Page 19: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/19.jpg)
Second step is slowHigh activation energy
Ea
![Page 20: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/20.jpg)
Second step is rate determining
![Page 21: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/21.jpg)
EnergySubstances tend react to achieve the
lowest energy state.Most chemical reactions are exothermic.Doesn’t work for things like ice melting.An ice cube must absorb heat to melt, but
it melts anyway. Why?
![Page 22: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/22.jpg)
EntropyThe degree of randomness or disorder.The first law of thermodynamics. The
energy of the universe is constant.The second law of thermodynamics. The
entropy of the universe increases in any change.
Drop a box of marbles.Watch your room for a week.
![Page 23: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/23.jpg)
Entropy
Entropy of a solid
Entropy of a liquid
Entropy of a gas
A solid has an orderly arrangement.A liquid has the molecules next to each
other.A gas has molecules moving all over the
place.
![Page 24: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/24.jpg)
Entropy increases when...Reactions of solids produce gases or
liquids, or liquids produce gases.A substance is divided into parts -so
reactions with more reactants than products have an increase in entropy.
the temperature is raised -because the random motion of the molecules is increased.
a substance is dissolved.
![Page 25: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/25.jpg)
Spontaneous reactionReactions that will happen.Nonspontaneous reactions don’t.Two factors influence.Enthalpy (heat) and entropy(disorder).
![Page 26: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/26.jpg)
Two FactorsExothermic reactions tend to be
spontaneous.Reactions where the entropy of the products
is greater than reactants tend to be spontaneous..
![Page 27: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/27.jpg)
EquilibriumEventually you reach a point where the
reverse reaction is going as fast as the forward reaction.
This is dynamic equilibrium.The rate of the forward reaction is equal to
the rate of the reverse reaction.The concentration of products and
reactants stays the same, but the reactions are still running.
![Page 28: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/28.jpg)
EquilibriumEquilibrium position- how much product
and reactant there are at equilibrium.Shown with the double arrow. Reactants are favored Products are favoredCatalysts speed up both the forward and
reverse reactions so don’t affect equilibrium position.
![Page 29: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/29.jpg)
Measuring equilibrium At equilibrium the concentrations of
products and reactants are constant. We can write a constant that will tell us
where the equilibrium position is. Keq equilibrium constant
Keq = [Products]coefficients
[Reactants]coefficients
Square brackets [ ] means concentration in molarity (moles/liter)
![Page 30: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/30.jpg)
Writing Equilibrium ExpressionsGeneral equation
aA + bB cC + dD
Keq = [C]c [D]d
[A]a [B]b
Write the equilibrium expressions for the following reactions.
3H2(g) + N2(g) 2NH3(g)
2H2O(g) 2H2(g) + O2(g)
![Page 31: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/31.jpg)
What it tells us If Keq > 1 Products are favored
If Keq < 1 Reactants are favored
![Page 32: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/32.jpg)
LeChâtelier’s Principle If something is changed in a system at
equilibrium, the system will respond to relieve the stress.
Three types of stress are applied.
![Page 33: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/33.jpg)
Changing Concentration If you add reactants (or increase their
concentration).The forward reaction will speed up.More product will form.Equilibrium “Shifts to the right”Reactants products
![Page 34: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/34.jpg)
Changing Concentration If you add products (or increase their
concentration).The reverse reaction will speed up.More reactant will form.Equilibrium “Shifts to the left”Reactants products
![Page 35: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/35.jpg)
Changing Concentration If you remove products (or decrease their
concentration).The forward reaction will speed up.More product will form.Equilibrium “Shifts to the right”Reactants products
![Page 36: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/36.jpg)
Changing Concentration If you remove reactants (or decrease
their concentration).The reverse reaction will speed up.More reactant will form.Equilibrium “Shifts to the left”.Reactants productsUsed to control how much yield you get
from a chemical reaction.
![Page 37: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/37.jpg)
Changing TemperatureReactions either require or release heat.Endothermic reactions go faster at higher
temperature.Exothermic go faster at lower
temperatures.All reversible reactions will be exothermic
one way and endothermic the other.
![Page 38: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/38.jpg)
Changing TemperatureAs you raise the temperature the reaction
proceeds in the endothermic direction.As you lower the temperature the
reaction proceeds in the exothermic direction.
Reactants + heat Products at high TReactants + heat Products at low T
![Page 39: Reaction Rate How Fast Does the Reaction Go Collision Theory l In order to react molecules and atoms must touch each other. l They must hit each other.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e925503460f94b987d7/html5/thumbnails/39.jpg)
Changes in PressureAs the pressure increases the reaction
will shift in the direction of the least gases.
At high pressure2H2(g) + O2(g) 2 H2O(g)
At low pressure 2H2(g) + O2(g) 2 H2O(g)