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Department of Chemistry and Biochemistry
1. Name one point you didn't understand in today's discussion.
2. List one fact you learned today.
3. After about one second after the Big Bang, what elements were present? H and He
4. What expanded during the Big Bang? Space!
5. What happened to temperature during the expansion after the Big Bang? It decreased.
( 20 points for each question - 100 perfect score)
1. Name two ways in which elements heavier than He (helium) could have been formed during the evolution of the universe.
(a) Helium burning (in nuclear reactions) (b) supernovae
2. A nuclear reaction that could form a carbon (C) nucleus in a star is:
He-4 + He-4
® Be-8 + He-4 (before Be-8 breaks up) ® C-123. The deuterium isotope (H-2) contains _1__ neutron and __1_proton.
4. Nuclear reactions cease during the Big Bang expansion because:
The temperature drops to the point where nuclear reactions cannot be sustained; positive ion repulsion is too great to be overcome in collisions; (neutrons have almost all decomposed).
5. All Chem 100 quizzes, tests, and the final exam are open book, open notes. (true or false?)
1. If two nuclei have different number of protons, they are different elements.
2. The main difference between the terrestrial planets (e.g., Earth) and the Jovian planets (e.g., Jupiter) is: terrestrials - closer to Sun and primarily solid; Jovian - further from Sun; primarily gaseous.
3. The atmospheres on the nine planets in our solar system are: (A) mainly water vapor; (B) mainly carbon dioxide; (C) all identical; (D) all different. (Nearly all aspects of the planets are different!)
4. The orbits of nearly all the planets lie in the same plane as the Sun because: (A) they were formed from the Sun; (B) the Sun attracted all the planets from other solar systems; (C) the Sun and the planets came from the same rotating disc; (D) that's the shape of the supernova that created our solar system.
5. Give the reason that two quite opposite processes are taking place in the universe at the same time: (1) space between all galaxies is continually expanding; (2) galaxies and stars are forming from the aggregation of matter. Density differences in different regions of space during early expansion after Big Bang.
1. During the early history of the Earth, many large rocks crashed into its surface and became part of the Earth, and: (A) gravitational energy was converted into heat energy; (B) the Earth was cooled by this event; (C) nuclear reactions were initiated; (D) this event caused living substances to form.
2. The origin of the early Earth's atmosphere is thought to be: (A) the Sun; (B) the Moon; (C) the interior of the Earth; (D) comet collisions.
3. The source of gaseous volcanic emissions: The material from the sea floor is subducted, heated, and vaporized, transported to the surface and emitted as hot volcanic gases.
4. The difference between a molecule and an atom is: A molecule is composed of atoms as fundamental constituents.
5. A valence electron in an F2 molecule differs from a non-valence electron in the following way: Valence electrons are shared between atoms whereas non-valence electrons belong to a single atom.
1. In sharing valence electrons, stability of the molecule is achieved because each atom attains the electron configuration of a noble gas.
2. The pressure of the atmosphere is lowered with increasing altitude because of gravitational attraction between the Earth and atmospheric atoms and molecules.
3. If two molecules have quite different masses one very high and one very low, at a given temperature, the molecule with the very low mass will have the higher average speed.
4. The reason for the formation of a dipole in the O-H bond of water is the very large differences in electronegativity between O and H.
5. Both the very high heat of vaporization of water, e.g., the number of calories necessary to transform a certain amount of water from liquid to steam and water's high boiling point, is due to the very strong hydrogen bonding between water molecules.
1. The geometry of the water molecule is ______ (bent, straight, cubic).
2. The O-H bond in the water molecule is _____ (covalent, ionic, polar covalent, polar ionic)
3. The centers of positive and negative charge in water are separated from each other and therefore cause the formation of a dipole.
4. A hydrogen bond between two water molecules can be broken by heating the water.
5. Water is a good solvent for polar or ionic compounds.
1. The source of nitric acid in acid precipitation is air.
2. The most highly oxidized chemical species of sulfur in the following series of compounds is:
H2S, S, SO2, SO3
3. Draw the Lewis Structure of ozone, O3 (hint: O3 and SO2 have the same number of valence electrons).
18 electrons, 9 pairs.
4. The difference between an acid and a base is that the acid is a proton donor and the base is a proton acceptor.
5. Both acids present in acid rain are (strong, weak, neutral) acids.
1. Show the formula for the acid in acid rain that originates from sulfur in coal. [H2SO4] Indicate in one or more chemical equations how this molecule behaves as an acid by releasing two protons.
H2SO4 + 2 H2O
® SO42- + 2 H3O+2. Show the Lewis formula of the species left behind when a proton is transferred from the nitric acid molecule to a water molecule.
3. Ammonia is a base because it accepts a proton.
4. HCO3- acts as a buffer because it reacts with an acid (or a base) in such a way that it prevents a significant change in pH.
5. Indicate a typical pH of each of the following:
a) a weak acid: ~ 2-4
b) neutral water exposed to air: ~ 5
c) a strong base: greater than 7, say 12
1. Hydronium ions can be obtained from which of the following: pure water, a strong acid, a weak acid, NH3?
2. Typical units employed in representing solution concentration are moles per liter.
3. If two moles of H3O+ are contained in two liters of aqueous solution, the H3O+ concentration is one M since there is one mole of H3O+ per one liter.
4. The pH of a solution of 0.0001 M HNO3 (10-4 M) is
-log10 (10-4) = -(-4) = 4
5. If the pH of a sample of Delaware rain is 7.5, your reaction is: one of skepticism, since air-saturated air has a pH of 5.5. Some neutralization of a pH 4 acid rain sample will probably not fully neutralize the sample. I suspect contamination and sample again.
1. According to the equations explaining the production of ozone in smog, if there is no sunshine there should be no smog -associated O3.
2. A photon of visible light from the Sun is absorbed by the Earth. Part of the energy of that light photon is emitted from the Earth in the form of infrared radiation.
3. The characteristic of the photon that causes it to be absorbed by a greenhouse gas is its oscillating electric dipole.
4. The characteristic of the greenhouse gas molecule that causes it to absorb an infrared photon is its oscillating dipole.
5. Which of the following is not a greenhouse gas: H2O, CO2, N2, NH3? [N2]
a) Greenhouse gas conc. are increasing; therefore global temperatures must also increase. Not necessarily; for example increased cloud cover caused by increased heat could reflect the sun's rays back out into space, thus cooling the Earth.
b) Without the existence of a chain-stopping reaction, a chain reaction could theoretically destroy all the ozone in the world. True, if the equations written are the only equations covering the situation; usually the equations are somewhat oversimplified. In the case of the ozone hole, nearly all the ozone is destroyed in one atmospheric region.
c) The steady state stratospheric ozone concentration is dependent upon the intensity of the infrared component of sunlight coming into the Earth. No, it is dependent on the UV component.
1. The steady state concentration of oxygen atoms in the stratosphere is very low because of the: (A) rapid reaction of oxygen atoms with oxygen molecules; (B) rapid recombination of oxygen atoms; (C) rapid reaction of oxygen atoms with CFCs; (D) interaction of oxygen atoms with photons.
2. One of the reasons the vortex winds in the Antarctic are important in the formation of the "ozone hole" is: (A) they prevent warm, ozone-rich air from mixing with cold, ozone-depleted air; (B) they quickly mix ozone-depleted air with ozone-rich air; (C) they harbor vast quantities of NO2; (D) they bring in moist, warm air which accelerates the ozone loss process.
3. The chain reaction postulated for the net lowering of the ozone layer concentration is initiated by the production of the free radical: (A) Cl; (B) ClO; (C) O2; (D) O3.
4. During polar spring in the Antarctic: (A) ice clouds melt, releasing chlorine atoms from their surface; (B) ultraviolet photons decompose ClONO2 radicals; (C) photons produce chlorine atoms; (D) vortex winds form.
5. HCFCs contain the following atoms: H, Cl, F, and C.
Each of the following statements is true or false. If true mark "T"; if false mark "F" & give a reason why it is false.
1. In the water cycle, the first pollution comes from air. T
2. Metal water pollutants in natural waters pass through soil unaffected. F - they are attracted to negative ions on humus or on uncoated soil particles.
3. Humus has a simple chemical structure. The main problem with humus in water pollution is getting rid of it. F - structure complex & you don't want to get rid of it!
4. Different layers of soil perform different functions in terms of purifying water draining through it. T
5. Water standing for long periods of time within pipes containing lead solder joints can be purified of lead ions by adding salt (NaCl) to it. F - a source of carbonate ions should be added to the water before or after it comes in contact with the lead in the solder to form lead carbonate.
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1. In an exothermic chemical reaction, the energy transformation is from chemical to heat energy.
2. Heat is a kinetic ("energy-in-motion") type of energy. The chemical species that are in motion are: atoms and molecules.
3. All fossil fuels have one thing in common. That is: They all contain carbon and hydrogen and combust in the presence of excess oxygen (under ideal conditions) to form carbon dioxide and water + heat.
4. (false)The first law of thermodynamics is valid most of the time, except in chemical reactions. The first law is valid under all conditions including chemical reactions.
5. Fission of the heavy, unstable U-235nucleus is made possible by (A) heating it; (B) absorption of a photon; (C) absorption of a thermal neutron; (D) a chemical reaction to produce high-energy products.
1. The paper plates in the Food Court were made of cellulose. Why don't we recycle the plates by eating them? Humans lack the enzyme necessary to digest those linkages.
2. What happens to the water of condensation in the formation of polyamides? Why is this necessary? It must be removed in order to drive the reaction to completion (Le Chatelier's Principle).
3. Products that can be remolded with heat are called thermoplastic.
4. Common products that are formed from thermosetting polymers include (name 2) _paint, shellac, varnish, resin, adhesives, epoxies, etc. (These cannot be remolded)
5. Kevlar is a particular kind of polyamide called a/an aramid. Its melting temperature is very much higher than a "normal" polyamide because of its aromatic (or planar) structure.
1. What is the ultimate source of the energy used by your right elbow during this class? The sun, through animal and plant intermediates.
2. Assuming a 2,000 Calorie diet, what is the recommended allotment for carbohydrates? 60% or 1200 Calories. How many grams is that? 1200 Cal./4 Cal./gram = 300 grams. (12 oz.)
3. Four grams of cellulose in your diet would provide how many Calories? Near ZERO, cellulose digesting enzymes not available.
4. When there is no glucose available from glycogen stores, how does the brain continue to function? Body uses protein sources--strips amino groups and uses carbon skeleton as energy source.
5. What is the fate of tissue repair if an essential amino acid is unavailable? If possible, strips amino acid from other body tissue, or the repair is not made.
1. Reducing the fats in your diet without replacing those Calories with carbohydrates will result in a loss of weight. True or False? Explain your answer. True, overall calorie consumption would be lower.
2. The "essential" fatty acids must be supplied by the use of dietary supplements. True or False? Explain your answer. False. Not necessary. Found in one Tablespoon of oil (e.g. salad dressing.)
3. The addition of two grams of an "essential" fatty acid to your diet will result in how many Calories? 18 Cal. [2 grams @ 9 Cal/gram.]
4. What are the sources of cholesterol in the body? 1) formed in the liver ("endogenous"), and 2) from animal food sources("exogenous") .
5. Cite one function of Vitamin C. How many Calories are furnished by 2 grams of this Vitamin? Antioxidant, tissue repair, iron absorption, etc. No energy is provided by this source.
1. The proper biological functioning of an enzyme is critically dependent on its molecular conformation.
2. An enzyme substrate is first adsorbed to the active center of an enzyme. Following this, the enzyme chemically alters the substrate.
3. A protein can be depolymerized (broken up into its constituent amino acids) by hydrolysis, i.e., adding back the elements of water to break the covalent bond. (Usually with the aid of an enzyme)
4. The ultimate high-energy chemical compound that is produced by the Krebs (TCA) cycle is ATP.
5. When a muscle gets a signal from the nervous system to contract, this desired movement is provided through a conversion of the chemical energy stored in ATP into mechanical energy after establishing contact between the actin and myosin molecules.
l. The function of the dendrites is to accept information from other cells through synapses.
2. Two functions of the proteins embedded in the neuron cell membrane are import of nutrients and export of waste; import and export of ions; receptor sites for neurotransmitters; reuptake of neurotransmitters;
3. Nerve signals travel from dendrite synapses through the cell body to axon terminal synapses.
4. Two questions that you have that relate to either habit-forming drugs or drug addiction are
(a)
(b) (Your responses will be summarized in class)
l. What chemical characteristic makes cocaine an addictive drug? Binds to receptor sites in synapse through H-bonding and dipole interactions, interferes with neurotransmitter uptake and ultimately alters the chemical composition of the synapse
2. Why is it so difficult to overcome addiction? Chemical changes in neurons and neuron pathways are not easily reversed, if they can be reversed at all.
3. Name two characteristics of addiction. Drug craving, high probability of relapse, ignore normal social bounds, loss of drug high, wanting systems rather than liking systems active, etc.
4. Is addiction thought to be a bad habit or an illness? An illness
5. A friend asks your advice about trying a new drug that is similar in chemical structure to cocaine but is claimed to be non-habit forming because it give less of a "high" and smaller "crashes." Your advice is: beware, it still has the same characteristics of a habit-forming drug and probably is just that!
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1. In the DNA polymer, there are three molecules that make up the fundamental repeating unit: sugars, phosphates, and bases.
2. On one DNA strand, the base sequence is ...GACCT.... On the opposite DNA strand in the double helix, the base sequence must be ...CTGGA....
3. RNA is a polymer that has one strand(s), contains only four bases, represented by the letters G, C, A, and U, and whose function is to direct the synthesis of a protein.
4. A polypeptide synthesized at the ribosomes folds into a protein, which may contain a number of different structural elements, two of which are helixes, pleated sheets, & turns.
5. The 3-dimensional structure of a protein determines its function in the body. If one amino acid in the protein is incorrect, the result may be a genetic disease.
l. The "I" in AIDS / HIV stands for immuno (deficiency)
2. In what way does HIV infection impair the immune system? Destroys critical T4 cells that direct immune system to destroy that which is foreign in the cell.
3. Name two ways in which one can interfere chemically with the HIV infection cycle? Interfere with docking; inhibiting the RNA® DNA step; inhibit the protease enzyme; build up immune system
4. What is the chemical cause of the drug resistance in fighting HIV infection? reverse transcriptase errors.
5. What question(s) do you have about HIV or AIDS that haven't been addressed either in the lecture or the book? (Write on the back of your card) These will be summarized in class.
1. Two methods available for prevention of HIV infection are: abstinence, use of a condom.
2. For HIV transmission from person A to person B to occur, one must have contact between blood, semen, or vaginal fluids from person A and blood, vaginal fluids or mucous membranes in person B.
3. What is the common characteristic of the chemicals used in combination therapy against AIDS? They are inhibitors of a natural enzyme process in the HIV cycle (e.g. inhibitor of reverse transcriptase or protease)
4. Is a person who tests HIV negative assured that they are free of HIV infection? NO! Why? Antibodies may not show up for several months.
5. Name three different sexual or other practices that can result in HIV infection: Hetero- or homosexual intercourse, oral or anal sex, needle sharing.
l. Name two applications of hydrogen bonding that have been emphasized in this course: dipole-dipole hydrogen bonding interactions to form liquid water; attractions between substrate and enzyme; helical arrangement in proteins; attractions between bases in DNA, etc.
2. What does the term "structure-function" mean in terms of polymers (e.g., biochemical molecules such as proteins or DNA or commercial polymers)? The 3-D arrangement (structure) of any polymer will determine the physical properties of a synthetic polymer (e.g. strength, dyeability and the function of a biological polymer such as an enzyme or other protein molecule.
3. The concept that I have learned in this course that helps most in my understanding of environmental problems is: (your choice)
4. The most fascinating or unexpected concept regarding chemistry that I have learned from taking this course is: (your choice)
5. My reaction to a new meaning for G-C and A-T bonding revealed today is: (your choice - many were shocked!)
Final Exam scheduled: Friday, December 12th, 10:30 - 12:30 in 311 Pearson Hall.
NOTE: 311 Pearson Hall is Studio A
**Review session scheduled for Wednesday evening, 7 - 9 pm in Brown Lab 101. **
Bring your questions!
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