Caitln+A

=Biomolecules= =Concentrated vs. Dilute and Strong vs. Weak= 1. A concentrated solution simply means there is a large amount of a substance compared to what it is dissolved in. For example, a concentration Kool-Aid solution would have a lot of suger dissolved in water. In contrast, dilute solutions are "watered down" in that there is little substance and a large amount of the solvent. A diluted Kool-Aid would not have much sugar in it and it would taste very watery. 2. Strong acids are very willing to give up their protons and as a result strong acids completely react with water. This means the resulting solution will only have ions dissolved. Weak acids are not as willing to give up their protons, so they do not react completely with water. 3. =Equilibrium 2= 1. When a chemical system reaches equilibrium the concentrations of the reactants and products remain constant because the forward reaction equals the reverse reaction. Even though the substances are constantly reacting the number of molecules present in the system remains constant, and in turn the concentration of these molecules remains constant. This does not mean that the equilibrium is not dynamic. The equilibrium //is// dynamic, but because the forward reaction equals the reverse reaction, there is not net change.
 * Carbohydrates** are composed of carbon, hydrogen, and oxygen and have several functions in our bodies. They can help store energy, they are present in DNA, and also assist in the body's development. Carbohydrates are found in starchy foods like breads and pastas. Two examples: monosaccharides, and disaccharides
 * Proteins** are made up of amino acids arranged in a linear fashion. Proteins work in a number of ways, including being enzymes, which speed up chemical reactions in our bodies. Proteins can also be structural proteins that hold the structure of our cell walls.
 * Lipids** are made up of fats, waxes, vitamins and sterols. Lipids help store energy, keep cell walls strong, and control some hormones. They can be found in most vegetable oils and cholesterol.
 * Nucleic acids** are made up of heterocyclic bases, sugars and phosphates and are present in the nucleus of cells. Their function is to carry genetic information. Two examples are deoxyribonucleaic acid (DNA) and ribonucleic acid (RNA)

2. The equilibrium constant (K) can be found in the following way. In a balanced equation: aA + bB <---> cC + dD, lowercase letter represent the coefficients while uppercase letter represent ions. The equilibrium constant is found by K=[C] c [D] d / [A] a [B] b, in which the [brackets] indicate the molarity of the ion, and this is raised to its coefficient in the balanced equation. Here are three examples of actual equilibrium expressions:

H 2 (g) <---> 2H(g) K = [H] 2 / [H 2 ] Hb(aq) + 4O 2 (g) <---> Hb(O 2 ) 4 (g) K = [Hb(O 2 ) 4 ] / [Hb][O 2 ] 4 N 2 (g) + 3H 2 (g) <---> 2NH 3 (g) K = [NH 3 ] 2 / [N 2 ][H 2 ] 3

3. Homogeneous equilibrium H 2 (g) + I 2 (g) <---> 2HI(g) K = [HI] 2 / [H 2 ][I 2 ]

Heterogeneous equilibrium: P 4 (s) + 6Cl 2 (g) <---> 4PCl 3 (l) K = 1 / [Cl 2 ] 6

=Equilibrium= An example of equilibrium outside the world of chemistry is that when it rains, the ground soaks up an equal amount of rain. The equilibrium can be affected by concentration, or how hard the rain is coming down. If the rain is coming down too hard then it will take longer for all of the rain to be soaked up by the ground. If the ground is very cold, it will take longer for the rain to be soaked up. If a lot of earth is available for the rain to soak through, it will go quicker than if it exposed to very little earth, or surface area. =Reaction Rates= [|Concentration and Reaction Rates] In this video a scientist mixes a solution of Hydrogen Peroxide and Sodium Iodide. When he uses a concentration of 3% Hydrogen Peroxide the foamy reaction is relatively slow. Then he used 30% Hydrogen Peroxide and the reaction is significantly faster. The faster reaction rate is because of higher concentration. The higher the concentration, the more likely molecules collide. A reaction can only occur when molecules collide.

[|Temperature and Reaction Rates] In this video we see how temperature affects the chemical reaction in glow sticks. A chemistry teacher breaks three glow sticks to make them light up, then places them in three seperate beakers all full of water varying in temperature. After a while, the glow stick in the hot water was significantly brighter than the glow stick in the cold water. Since the former had a higher temperature, the molecules inside the glow stick were moving faster. Faster moving molecules lead to more collisions, and a faster reaction.

[|Catalysts and Reaction Rates] Catalysts offer a a different way for a reactant to change to a product that requires less energy than without a catalyst. Since it requires less energy, the reaction can happen faster.

[|Surface Area and Reaction Rate] In this video a chemist demonstrates reactions with the very flammable lycopodium powder. When just a pile of the powder is exposed to flame, nothing happens. When the powder is sprinkled into the flame it is set on fire. Surface area increases the reaction rate because more of the reactant is exposed, so there are more collisions. =Immiscibility and Solubility= After an oil spill clean-up teams need to worry about containing the oil, removing it, and cleaning up what the oil has already affected. Information found from [|Oil Spill Basics]
 * Oil trapped in bird's feathers can prevent them from flying and oil in animals' fur can remove insulating qualities, so clean-up teams often bathe affected animals with detergent. Perhaps you've seen commercials for Dawn dishwashing fluid that has been used in oil spills. Contrary to belief, however, oil has little effect on the fish in the area.
 * Right away oil is usually contained with boons to prevent from it from spreading.
 * Skimmers remove the oil from the surface. One technique of skimmers uses centripetal force. The liquid is spun and since water is heavier than oil it spins out further so the oil can be collected.
 * Sometimes the oil is burned on the surface. While this does create a TON of black smoke, it's not any worse for the environment than what the oil was probably intended to be used for anyway.

Solubility is a property of a solute that describes how much of it can be dissolved in a given amount of solvent. Rate of dissolution is how fast a solute dissolves in a solvent. Information found from [|Solubility]
 * Temperature: For solid solutes, in increase in temperature of the solution equals an increase in solubility, whereas solubility of gases decreases as temperature rise.
 * Stirring: Stirring exposes fresh solvents and solutes to each other, which increase the //rate of dissolution// (how fast a solute dissolves) but not necessarily the solubility.
 * Surface Area: Similar to stirring, a greater surface area means a greater rate of dissolution, but not necessarily a greater solubility.
 * Temperature: Particles move faster at higher temperatures meaning that the particles are being exposed to each other more frequently than at a lower temperature. Increasing temperature will likely increase rate of dissolution.
 * Stirring and Surface Area: see above

**Properties of Water** =The Greenhouse Effect= Light, described as a wave of energy, comes to Earth from the sun. It is re-emitted from the Earth in a form of light call infrared. Now the molecules in our atmosphere are constantly in motion. They pull and twist at certain frequencies. Some molecules move at the same frequency of the infrared light from the Earth. When this happens the infrared waves are reflected and can go anywhere. This keeps the heat locked in our atmosphere, causing a greenhouse effect.
 * Water has a high specific heat, at 1 calorie / gram o C. Specific heat is the amount of energy, or heat, required to raise the temperature of a specific amount of a substance on degree Celsius. To say water has a high specific heat means it takes a lot of energy to make its temperature rise. This is why a lake is typically cooler than the sand, and why water is used to keep and engine of a car cool. It is also why it takes water so long to boil. [|Specific heat]
 * Water exists on Earth in three stages: liquid, gas, and solid. It is the only common substance able to do so. Earth's temperature allow water to exist at these three stages and to even change stages. [|Three stages]
 * Water has a high surface tension, meaning the bonds holding it together are stronger than its bonds to a material. As a result, we see beads of water form as opposed to just a puddle. [|Surface tension]
 * Water's boiling point is 100 o C at 1 atm. We know water' boiling point is relatively high because of its high specific heat, as discussed above. [|Boiling point]
 * When it comes to pH levels, water is neither acidic nor basic. Most substance are at least a little acidic or a little basic, but water is pure. pH level is the measure of acidity of a substance. [|pH level]

Global warming is entirely because of human emissions. While humans are producing more CO2 than ever, and this does contribute to a global warming, the Earth goes through natural cycles of heating and cooling. The Greenhouse Gases also cause a natural warming of the Earth. The melting glaciers are proof of Global Warming.

[| The Illusion of Skin Color] In this Ted Talk Nina Jablonski discusses the evolution of human pigmentation. I chose this talk because the idea of evolution fascinates me. Also, skin color is a topic that transcends the fields of science. When discussing the migration of peoples to lands not conducive to their pigmentation, we are not just discussing the scientific and anatomical principles of skin, but the situations regarding health and society that accompany it. This makes the topic of the evolution of skin color very practical and applicable in the real world.

During his travels Charles Darwin discovered the many colors of skin present on the planet but dismissed the idea that this variation had anything at all to do with climate. However, a NASA satellite was able to measure the amount of radiation from the sun at the Earth's surface, publishing the findings that radiation is highest around the equator and lowest near the poles. The amount of radiation of the sun directly relates to the darkness of the skin of the people living in the given area, with darker skin tones near the equator and very fair skins near the poles. Even though Darwin dismissed this theory we still see his ideas of natural selection when we study the history of human pigmentation. The oldest humans had very dark skin as they resided in central Africa near the equator. The high amount of UVB radiation produced high amounts of vitamin D in these people's skin. As a natural defense against harmful radiation early human's bodies began to produce larger amounts of melanin, essentially what pigments skin. Over time early humans migrated to places that received less UVB radiation, and so their vitamin D levels decreased and the amount of melanin in their skin decreased. This is how the broad spectrum of skin tones began to develop. Fairly recently, however, people have migrated to new places for which their skin is not adapted. The Trans Atlantic Slave Trade, for instance, brought thousands of deeply pigmented African people to the Americas and Europe, and to latitude levels that receive substantially less UVB radiation. Millions more around the Earth have immigrated to countries that may be very different than their own. The result is this: lightly pigmented people exposed to high amounts of radiation have to worry about damage to their skin, and potentially the development of skin cancer, while darkly pigmented people exposed to very little amounts of radiation may have deficiency of vitamin D.

Before watching this Ted Talk I was already aware of the relationship between proximity to the equator, amount of radiation from the sun, and amount of pigment in skin. I was not aware, however, the reason why skin develops this way or how humans have evolved so that we have a broad spectrum of skin tones. I think the idea of evolution is fascinating and what is even cooler to me is that we have proof of it right in such a visible place: our skin.