```"Mining an Ore"Teresa Granito                 Von Steuben Metropolitan Science Center                               5039 Kimball                               Chicago IL 60625                               312-534-5100   MR#51Objectives:The high school students will be able to:      1.  calculate percentages     2.  read chemical formulas     3.  determine the molar mass of a compound     4.  differentiate between an ore and a mineral     5.  calculate the percent composition of a mineral in an ore     6.  determine which ore has the greatest percentage of mineral     7.  do a Performance Assessment activity to demonstrate masteryMaterials needed:     1.  "ore" = two brands of chocolate chip cookies (2 per lab group)     2.  "mining tools" =  paper clip, forceps, etc.     3.  balance     4.  periodic tableStrategy:Part I  (calculating percentages)Remove a "precious mineral" from an "ore".  The "ore" will be the chocolate chip cookie and the "mineral" will be the chocolate chips.  The object is to determine which "ore" has the greatest percentage of "mineral".      1.  find the mass of a cookie      2.  separate chips from cookie using "mining tools"     3.  find mass of chips     4.  determine the percentage of chips in the cookie:           mass of chips
mass of cookie  x   100%  =  percent of chips in cookie
5.  repeat with second cookie
6.  compare results

Part II (percent composition of an ore)

Define
1.  chemical formula
2.  molar mass
3.  mass number
4.  periodic table of elements
Do some example problems with students:
5.  What is the percent composition of Ag in AgS?
Ag = 1 x 108g = 108g            108gAg
S = 1 x  32g =  32g           140gAgS  x 100 = 77% Ag in AgS
140g

Data Chart
ORE       MASS OF    MASS OF    PERCENT OF    PERCENT OF
ORE      MINERAL    MINERAL       WASTE
--------------------------------------------------------------------
Al2O3          CaSO4

Performance Assessment:     Because of your superior mining ability you have been awarded your choice      of one of two mining locations.  One site, located in Mexico, is rich in      Chalcopyrite (CuFeS2).  The other site, located in Russia, is rich in      Chalcocite (Cu2S).       Which location would you choose to mine?  Explain all aspects of your      decision.                                DIG AWAY!
Scoring Rubric
DEMONSTRATED COMPETENCE

For 6 points:    The response is exemplary.
- an explanation that is complete
- molar masses and percent composition calculated precisely
- all aspects of decision looked at completely
- more than one explanation that is complete and correct
- well thought out answer

For 5 points:    The calculations are correct and the response is clear.  Not
all aspects taken into consideration.

For 4 points:    The calculations are correct, but the explanation lacks
clarity.

SATISFACTORY RESPONSE

For 3 points:    The response indicates a partial solution.  Perhaps the molar
masses are correct, but the percentages are done incorrectly,
or vise versa.