Return to Chemistry Index"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 chipsmass 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 = 108g108gAgS = 1 x 32g =32g140gAgS^{x 100 = 77% Ag in AgS}140g Data Chart ORE MASS OF MASS OF PERCENT OF PERCENT OF ORE MINERAL MINERAL WASTE -------------------------------------------------------------------- Al_{2}O_{3}

CaSO_{4}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 (CuFeS_{2}). The other site, located in Russia, is rich in

Chalcocite (Cu_{2}S).

Which location would you choose to mine? Explain all aspects of your

decision.

DIG AWAY!Scoring RubricDEMONSTRATED 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. INADEQUATE RESPONSE For 2 points: The response indicates a partial solution. Or, the response indicates the student may understand the solution, but the explanation is incoherent. For 1 point: The response is incorrect, but it shows evidence of mathematical and logical reasoning. A mathematical explanation is developed. The explanation, however, does not address the crux of the problem or the essence of the solution. For 0 points: The student leaves a blank page or writes, "I don't Know."