Name ________________________________________________________________
331.208
194.188
323.192
101.102
Pb(NO3)2(aq) + K2CrO4 (aq)  PbCrO4 (s) + 2KNO3(aq)
1.
2.
3.
4.
5.
Label a clean, dry beaker with your initials and “A” and find the mass of the beaker.
Zero the balance and add approximately one gram of Pb(NO3)2 to beaker A. Record the mass of Pb(NO3)2 .
Label a clean, dry beaker as “B” and find the mass of the beaker.
Zero the balance and add approximately one gram of K2CrO4 to beaker B. Record the mass of K2CrO4.
Add approximately 10 mL of distilled water to each of the beakers and swirl to dissolve. The Pb(NO 3)2 may need warming
to completely dissolve.
6. When both solutions are completely dissolved, pour the yellow K2CrO4 solution into the clear Pb(NO3)2 solution. Swirl
gently to mix. Heat for five minutes to allow for a complete reaction, but don’t let it boil over!
7. Fold and label a piece of dry filter paper and find its mass.
8. Place beaker B under the funnel and pour the contents of beaker A into the filter paper.
9. When filtering is complete, place the filter paper inside beaker A and place in an oven to dry.
10. Place beaker B on a hot plate to boil off the water. When completely dry, allow time to cool before finding its mass.
11. Find the mass of beaker A with the filter paper and the dry product.
Mass of beaker A
Mass of Pb(NO3)2
Mass of beaker B
Mass of K2CrO4
Mass of clean, dry filter paper
Mass of beaker B with contents after drying
Mass of the dry products in beaker B
Mass of beaker A with filter paper and dry PbCrO4
Mass of dry PbCrO4 (actual yield)
1. Which reactant was in excess?
Which reactant was limiting?
2. Calculate the mass of excess reactant that should theoretically be left over (not used in the reaction)?
3. Where is the excess reactant at the end of the experiment?
What is mixed with it?
4. Calculate the theoretical yield of PbCrO4 that should have been produced in your reaction?
5. What could account for any difference between your actual and theoretical yield of PbCrO4?
6. What is the combined mass of both reactants you started with?
7. What is the combined mass of the products you ended up with, including the mass of any unused reactant?
8. Should the answer to #6 and #7 be the same?
Why?
If they are not the same explain why they aren’t.