Application of Equilibrium

By: Stephanie, Shawna, and Amber

EATING SUGAR AND TOOTH DECAYSTEPHANIE LEHSTEN

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.

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.

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)

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.

Tooth decay andLe 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

Effects of Tooth Decay• Cavities• Toothache• Pain• Sensitivity

– Hot and cold foods

• Infection• Gum Disease

• Swelling• Visibly discolored teeth• Difficulty sleeping,

paying attention• Heart Disease• Digestion Problems

Carbon Monoxide PoisoningAmber Gratz

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.

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)

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.

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.

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.

Effects on HumansConcentration Symptoms

35 ppm (0.0035%) Headache and dizziness within six to eight hours of constant exposure

100 ppm (0.01%) Slight headache in two to three hours

200 ppm (0.02%) Slight headache within two to three hours; loss of judgment

400 ppm (0.04%) Frontal headache within one to two hours

800 ppm (0.08%) Dizziness, nausea, and convulsions within 45 min; insensible within 2 hours

1,600 ppm (0.16%) Headache, dizziness, and nausea within 20 min; death in less than 2 hours

3,200 ppm (0.32%)Headache, dizziness and nausea in five to ten minutes. Death within 30 minutes.

6,400 ppm (0.64%)Headache and dizziness in one to two minutes. Convulsions, respiratory arrest, and death in less than 20 minutes.

12,800 ppm (1.28%) Unconsciousness after 2–3 breaths. Death in less than three minutes.

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.

Chlorofluorocarbons and Ozone Depletion

Shawna Rivedal

• 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)

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

• 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

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

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

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

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