Download Homework Assignment #4

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: [email protected] or [email protected] 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+ ?