405 Stoich Lab Part 2:   Sodium Hydroxide reacts with Chromium (III) Nitrate
  • Write all answers in your bound journal
  • Make it NEAT and in COMPLETE SENTENCES, clearly identify which section you are working (using numbers)
  • Box final answers if doing math.
  • -4pt if you do not title and date the entry
  • -1pt (per infraction) if you do not clearly identify the sections, or number the problems

 
    LAB PROTOCOL (20 pts)
     
  1. For the following reaction (sodium hydroxide and chromium (III) nitrate), show the:
    1. Molecular equation
    2. Name the type of reaction
    3. Predict the solubility of the reactants and the products
    4. Write the complete ionic equation
    5. Write the net ionic equation
  2. You will use an excess of sodium hydroxide solution (30ml of a 0.500M) to percipitate out what ionic compound?
  3. HYPOTHESIZE: How you would determine the molarity of chromium (III) nitrate based on the mass of the reaction percipitant?
  4. Show and explain the experiment to Dr. Duick before starting!
  5. Start with 20.00ml of your unknown chromium (III) nitrate solution.
  6. Add 30ml of a 0.500M sodium hydroxide solution to the chromium (III) nitrate solution.
  7. What compound are you seeing?
  8. Measure the weight of the filter paper and write it (in pencil) on the edge filter paper.
  9. Decant the solution onto the filter paper, be careful in trying to contain all of the percipitant.
  10. Let the filter dry overnight in the fume hood, it will be weighed the next class meeting time.
    NEXT MEETING TIME
  11. Weigh the filter paper and product.
  12. Subtract the mass of the filter paper (written on the edge) to get just the mass of the product.
  13. Using the mass, determine the molar concentration of the chromium (III) nitrate solution.
  14. Using Stoichiometry, determine the molarity of nitrate, and sodium ions that remained in 50.0ml of solution?
  15. Show your results to Dr. Duick, and get the theoretical concentration
    (keep it secret from your classmates).
  16. What is your percent yield of the product? (Percent Yield = (Actual Yield/Theoretical Yield) x 100%)
  17. What is your percent error for product recovery? (Percent Error = ((Theoretical Yield - Actual Yield)/ Theoretical Yield) x 100%)
  18. If percent yield or percent error resulted in unexpected values, what might have contributed to these results?