3. Increased Risk Factors of Tooth Decay
• Eating a diet rich in sugar and starch
• Sticky foods
– more likely to remain on the surface of the teeth.
• Snacking increases how long and how often acids
are in contact with the teeth.
4. Tooth Decay
• The bacteria in your mouth consumes sugar from the
food you eat and produces acids.
• Some acids attach to your teeth and form
plaque, which coats the teeth and traps the acids next
to the surfaces. The acids slowly dissolve the hard
enamel surface of the teeth.
5.
6. Equilibrium Equation
• Enamel is composed of a strong, insoluble mineral
called hydroxyapatite, Ca5(PO4)3OH.
• The equilibrium equation is:
– Ca5 (PO4 )3 OH(s) 5Ca 2+ (aq) + OH - (aq) + 3PO4 3-
(aq)
7. Dynamic Equilibrium
• Equilibrium exists when two opposing reactions
occur at the same time and rate.
• The forward and reverse reactions may occur at
different rates.
• In children's teeth, mineralization usually occurs
faster than demineralization.
• In adults, the processes may take place at about the
same rate-equilibrium.
• However, if the acid becomes highly concentrated
at a specific point on a tooth, demineralization
occurs, leading to a cavity.
8. Tooth decay and
Le Chatelier’s Principle
• 1. Ca5(PO4)3OH(s) 5Ca2+(aq) + 3PO43-(aq) + OH- (aq)
Add sugar…
• 2. Bacteria + sugar acid (H+)
• 3. H+ + OH- H2O
• OH- formed by the dissociation of enamel (rxn. 1) reacts with
the acid (rxn. 3). This causes the concentration of OH- to
decrease and according to Le Chatelier’s principle, rxn 1 will
shift right to form more OH-.
• Further dissociation of Ca5(PO4)3OH(s) will occur resulting in
tooth decay
• The more acidity in your mouth, the greater chance for tooth
decay
11. Chemistry of the Blood
• Oxygen is transported around the body in blood by
the complex molecule hemoglobin, a globular
protein which has a central iron atom.
• When hemoglobin reacts with
oxygen, oxyhemoglobin is formed.
• The oxygenation of blood is an equilibrium reaction.
• Carbon monoxide, CO, also readily reacts with
hemoglobin which can result in carbon monoxide
poisoning.
12. Dynamic Equilibrium
• A dynamic equilibrium exists once a reversible
reaction ceases to change its ratio of
reactants/products, but substances move
between the chemicals at an equal rate, meaning
there is no net change.
• Hb(aq) + CO(aq) -> HbCO(aq)
OR
• Hb4(aq) + 4CO(aq)-> Hb4(CO)4(aq)
13. Stress of Equilibrium
• The equilibrium constant for this reaction is very
large, so there is very little hemoglobin left to react
with oxygen. The cells in the body will be starved of
oxygen because carbon monoxide rather than
oxygen is being transported.
• Because the equilibrium constant for the carbon
monoxide reaction is so large, low concentrations of
carbon monoxide can be harmful.
• Because the reaction is reversible, carbon monoxide
poisoning can be counteracted, if caught earlier
enough, just by providing sufficient oxygen.
14. Le Chatelier's Principle
• When a system at
equilibrium is disturbed, the
equilibrium position will
shift in the direction which
tends to minimize, or
counteract, the effect of the
disturbance.
• Oxygen VS. Carbon
Monoxide, however unless
substantial amounts of
Oxygen are added, the
Carbon Monoxide will not be
counteracted.
15. What Can Produce CO?
• Older motor vehicles
• Gasoline powered tools
• Heaters
• Cooking equipment
• Tobacco smoke
• Concentrations of 100 ppm or higher can
negatively effect human health.
16. Effects on Humans
Concentration Symptoms
Headache and dizziness within six to
35 ppm (0.0035%)
eight hours of constant exposure
100 ppm (0.01%) Slight headache in two to three hours
Slight headache within two to three
200 ppm (0.02%)
hours; loss of judgment
Frontal headache within one to two
400 ppm (0.04%)
hours
Dizziness, nausea, and convulsions
800 ppm (0.08%)
within 45 min; insensible within 2 hours
Headache, dizziness, and nausea within
1,600 ppm (0.16%)
20 min; death in less than 2 hours
Headache, dizziness and nausea in five
3,200 ppm (0.32%) to ten minutes. Death within 30
minutes.
Headache and dizziness in one to two
minutes. Convulsions, respiratory
6,400 ppm (0.64%)
arrest, and death in less than 20
minutes.
Unconsciousness after 2–3 breaths.
12,800 ppm (1.28%)
Death in less than three minutes.
17. Effect on Environment
• Carbon monoxide can affect the amount of other
greenhouse gases, which are linked to climate
change.
• Very high levels of carbon monoxide will cause the
same problems for birds and animals that are
experienced by humans, although these levels are
unlikely to be experienced in the
environment, except in extreme events such as
bushfires.
• The Clean Air Act requires EPA to set national air
quality standards for specific harmful pollutants.
19. • Chlorofluorocarbons: Any of various
halocarbon compounds consisting of
carbon, hydrogen, chlorine, and fluorine, once
used widely as aerosol propellants and
refrigerants
• Ozone: a colorless, odorless reactive gas
comprised of three oxygen atoms
– Found naturally in the earth’s stratosphere by
electric discharges
– Absorbs the UV component of incoming solar
radiation (harmful to life on earth)
20. Dynamic Equilibrium
• Free radicals react with oxygen molecules to
form ozone
• Absorption of energy light radiation also
triggers decomposition of ozone
• Dynamic equilibrium of formation/destruction
+ +
O - - O
O O O O
21. • CFC molecules:
– CFCl3 or CF2Cl2
– Carbon, Fluorine, Chlorine
• Extremely stable: able to slowly travel from
troposphere to atmosphere
– Energetic photons break down the CFC molecules:
• Cl- able to destroy ozone
22. Ozone Destroying Cycle of Cl- atoms
• Cl + O3 → ClO + O2
• ClO + O → Cl + O2
• O3 + O → 2O2
– (O3=ozone)
– Cl- is a catalyst
• Initiates breakdown of ozone to form two O2 molecules
NO2 + O2 NO + O3
23. Stresses on Equilibrium
• Increase in (O)
– Result:
• Shift toward production of ozone
– To keep Kc constant
• Catalyst
• Reduction in Ptotal
• Increase in temperature
– Exothermic reaction
– Ozone (O3) likely to decompose back into O2
24. Le Chatelier’s Principle
• With increased pressure:
– Shifts equilibrium towards reactants to reduce
increase of heat
• With decreased Ptotal :
– Shifts equilibrium towards reactants
• B/c more gas molecules to help increase pressure
25. Effect on Environment
• Hole in ozone would lead to
detrimental, biological impacts
– Increased UV exposure
• Damaged early development
• Increased risk of cancer:
– Animal skin, eyes, and immune systems
– Impaired plant growth
– Reduced plankton production
• Are the foundation of aquatic food webs
Editor's Notes
Plaque is made up of food debris, saliva and the bacteria that are normally present in the mouth, and convert food into acids. It contains acids which, over time, can dissolve away the protective, hard enamel coating of the tooth, and create holes, or cavities.
Many heart diseases are related to bacterial infection. The bacteria reaches the heart through the blood stream, and the starting point is through your gums. Decaying teeth lead to damaged gums provide a way for bacteria to invade the inner body.
