hw4 - BIO 5099 Homework Assignment #4

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Unformatted text preview: BIO 5099 Homework Assignment #4 Name_____________________________________ Due start of class, Tuesday September 17th. Late assignments are not accepted, show your work for partial credit. Assignments may be e-mailed to: christiaan@xiaan.com or rbaror@dmibio.com anytime, or faxed to (303) 556-2889 between 3:00 and 4:00 p.m. on Tuesday. Define in your own words and give an example: 1. (2pts) Catalyst 2. (2pts) Gibbs Free Energy 3. (2pts) Exothermic 4. (2pts) pH 5. (4 pts) Each of the following phenomena is a direct result of a physical or chemical property. Place a check next to the correct answer: a) Phys Chem An iron nail is attached to a magnet. b) Phys Chem Sugar caramelizes upon heating above its melting point. c) Phys Chem A bronze statue develops a green coating over time. d) Phys Chem Water is boiled. 6. (4 pts) Indicate whether each sample of matter listed is a mixture or pure, if mixture, then indicate whether the mixture is homogeneous or heterogeneous: a) A cube of sugar is a _________________________________________ . b) Premium gasoline is a ________________________________________ . c) Tap water is a ______________________________________________ . d) Granite is a ________________________________________________ . For the following exercises, you will need a periodic table. Check the course web site for useful links. 7. (4 pts) The amino acid methionine has the molecular formula of C5H11NO2S. a) Its molecular weight is: b) The number of moles of H in 6.5 moles methionine is: c) The number of C atoms in 3 moles of methionine is: d) The number of grams of O per gram N is: 8. (3 pts) Consider the combustion of pure octane (C8H18) with oxygen (O2) to make carbon dioxide (CO2) and water (H2O) a) Write a balanced chemical equation for this reaction: b) If we have 10g of octane, how much oxygen (in grams) do we need to fully combust all of the octane? c) How many moles of carbon dioxide are produced? d) For the reaction above, indicate the oxidation states for each element in the following species: O2, CO2, and H2O (extra credit for octane). e) In this reaction, which elements (if any) are reduced? f) In this reaction, which elements (if any) are oxidized? 9. (4 pts) Molarity is defined as (number of moles of solute)/(number of liters of solvent) and is expressed using the symbol M. a) If we dissolve 10g of NaCl in 35 ml water, what is the Molarity (or molar concentration) of NaCl? b) How much water is needed to make a 100 mM (milli-molar) solution given 0.3g of sucrose (C12H22O11)? 10. (2 pts) Draw a feasible structure for an uncharged molecule of C8H12O2 (hint: remember double bonds!) 11. (5 pts) Recall that for a reaction: aA + bB cC + dD, the equilibrium constant Kc is given by : [C ] c [ D] d Kc = [ A] a [ B] b If you have the following reaction and equilibrium constant: CO + 2H2 CH3OH Kc= 14.5 a) What will be the concentrations of all of the species at equilibrium if we begin with 1 mole of CO and 1 mole of H2? b) What are the conditions on Kc needed to make the reaction tend to the right? c) What are the conditions on Kc needed to make the reaction tend to the left? 12. (2 pts) If you have a solution of water with a pH of 3.7 what is the concentration of H+ ? ...
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