Here Comes the Fuzz Lab

Essential Question: How much product can a chemical reaction yield? What limits the yield of a chemical reaction? How accurate are stoichiometric predictions?

Start Lab Do Day 1 Procedures before the Prelab Analysis.

MSDS & LD50s MSDS = Material Safety Data Sheet LD50 = Lethal Dosage for 50% of test animals. Search for MSDS resource links to determine the LD50 of copper(II) chloride & hydrochloric acid. (Google Search).

Prelab Analysis Part A. The Balanced Chemical Equation: ___+_______*2H 2 O  ___ + ______ + H 2 O. The reaction is a single replacement reaction using the lowest possible charge.

Prelab Analysis Part B Predicting Quantities Given the mass of iron added to the reaction: a.Determine the mass of copper that can be produced. b.Determine the mass of CuCl2*2H2O that would react with the iron. Fe + CuCl 2 *2H 2 O  Cu + FeCl 2 + H 2 O ~2.5g b.?g a. ?g

Prelab Analysis Part B Predicting Quantities (continued) Given the mass of iron added to the reaction: a.Determine the mass of copper that can be produced. b.Determine the mass of Fe that would react with the iron. Fe + CuCl 2 *2H 2 O  Cu + FeCl 2 + H 2 O b. ?g ~4.00g a. ?g

Determining the Limiting Reactant What 2 substances are reactants? What is the only product we calculate in the lab? Which reactant theoretically produces the least product? Is there enough of the CuCl2*2H2O to react completely with the Fe? Is there enough Fe to react completely with the CuCl2*2H2O?

Writing the Hypothesis Write the hypothesis trusting that the Limiting Reactant determines the outcome. If ____ grams of (limiting reactant) are allowed to react with ____ grams of (excess reactant), then ____ grams of (product) will be produced and ____ grams of (excess reactant) will be left over because …

Appropriate Procedures Day 1 __0. Check off each step as you go. __1. Always use the same scale to avoid systematic error. __2. Record observations at each step. __3. Prepare an organized table of measurements and observations. __4. Label plastic cup with period & initials __5. Mass the dry clean plastic cup.

Day 1 (continued) __6. Use 2 nails __7. Sand the iron nails clean before the reaction. __8. Record the mass of the 2 nails once. __9. Measure about but not exactly 4.00g +/-.01g of CuCl2*2H2O into your plastic cup. __10. Add 50 ml of distilled water to the cup. __11. Place the nails in the copper (II) chloride solution. __12. Allow the reaction to sit over night to reach completion.

Day 2 __Put on goggles before obtaining your sample. __Make detailed observations of your experiment before moving forward __13. Use tongs to remove the iron nails and place them on a paper towel to dry. __14. Record the mass of the 2 nails again at the end when they are dry. __15. Carefully decant the remaining liquid into the waste bucket saving the solid precipitate.

Day 2 (continued) __16. Clean the solid copper residue 3 times total with ___a. With a 25 ml rinse of distilled water. ___b. With a 25 ml rinse of 1M HCl. (waste bucket!) ___c. Rinse one last time with another 25 ml of distilled water. ****Decant carefully after each rinse. __17. Place the solid copper residue and plastic cup on the counter to dry overnight.

Day 3 – Record all observations __18. Remass the plastic cup and its dry contents. __19. Show the instructor your recovered copper and recycle it into the designated container. __20. Dispose of your plastic cup out thoroughly for the next lab.

Post Lab Analysis A.Calculate the amount of iron lost: Fe (lost) = Fe (before) – Fe (after) B.Calculate the amount of copper produced? Cu = (Cu + Cup) - Cup

Percent Yield & Percent Error How much Cu did you recover compared to your calculations? %Yield Cu = (actual Cu / theoretical Cu)x100% How close was the mass lost in the nails to what you predicted? %Error Fe = [(actual Fe (lost) – theoretical Fe (lost) )/theoretical Fe (lost) ] x 100%

Here Comes the Fuzz Lab Report (1 of 3) Title Essential Questions Hypotheses (if, then, leftovers, because…) Materials (include LD50s) Procedures (rearranged and edited logically – don’t copy & paste from powerpoint) Data & Observations (Steps, Measurements, Observations)

Here Comes the Fuzz Lab Report (2 of 3) Analysis/Calculations (8 calculations/ 12 points) –Item / Strategy-Formula / Work / Answer –4 Prelab analysis calculations –Actual amount of Fe lost –Actual amount of Cu produced –% Yield of Cu produced –% Error of Fe used Sources of Error – at least 2 for real issues that may have thrown off the results (Hints: moisture, decanting, nails, etc.)

Here Comes the Fuzz Lab Report (3 of 3) Conclusions A)Revisit & evaluate hypothesis. Support your evaluation with numbers from the lab. B)Revisit each of the 3 essential questions. C)Which was the limiting reactant? Which was the excess reactant and how could you tell for each? D)Describe how stoichiometry is used in real life by professionals. (Hint: Look in Chapter 11) E) Extra Credit: Relate slang title to lab