Here Comes the Fuzz Lab Here Comes the

Here Comes the Fuzz Lab

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

Prelab Analysis Part A. The Balanced Chemical Equation: ___+_______*2 H 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 Cu. Cl 2*2 H 2 O that would react with the iron. Fe + Cu. Cl 2*2 H 2 O Cu + Fe. Cl 2 + H 2 O ~2. 5 g 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 + Cu. Cl 2*2 H 2 O Cu + Fe. Cl 2 + H 2 O b. ? g ~4. 00 g 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 Cu. Cl 2*2 H 2 O to react completely with the Fe? • Is there enough Fe to react completely with the Cu. Cl 2*2 H 2 O?

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. 00 g +/ -. 01 g of Cu. Cl 2*2 H 2 O 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 1 M 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)x 100% 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 LD 50 s) 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