Mass-Mass Relationships in Reactions

Purpose: To compare the theoretical mass of one of the products of a double replacement reaction to the experimentally determined mass of the same product.

Equipment

Balancering stand

Graduated cylinder, 100-mLiron ring

Beakers, 250-mL (2)funnel

Beaker, 100-mLsafety glasses

Stirring rod

Materials

Lead (II) nitrate (Pb(NO3)2Filter paper

Potassium iodide (Kl)

Procedure

  1. Using the balance, measure out exactly 1.1g of lead (II) nitrate (Pb(NO3)2). Record this mass as (a) in your data table.
  2. Place the Pb(NO3)2 in a clean 250-mL beaker and add 50.0mL water. Stir thoroughly to make sure all crystals are dissolved. Rinse off the stirring rod.
  3. Measure out approximately 1.2g of potassium iodide (Kl). Place it in a clean 100mL beaker and add 50.0mL of water. Stir until all crystals are dissolved.
  4. Pour the Kl solution into the 250-mL beaker containing the Pb(NO3)2 solution. Stir. Record your observations as (d) in your data table. When you stir be careful not to be messy.
  5. Find the mass of a piece of filter paper. Record this as mass (b). Fold the filter paper and place it in the funnel as shown in Figure 28-1. Pour slowly. Do not allow the liquid to rise above the edge of the filter paper in the funnel. Stir with each pouring to get as much solid out as you can each time.
  6. Rinse the beaker with about 20mL of water. Pour the rinse water through the filter. Repeat the rinsing and filtering until all the precipitate is out of the beaker.
  7. Wash the precipitate by pouring about 10mL of clean water through the filter.
  8. Remove the filter paper and precipitate from the funnel and place in an oven or in your lab drawer to dry. Use 2 paper towels, put your name on them and put the solid in the fume hood.

Tomorrow

  1. Mass the dry precipitate + filter paper (mass © in our data table)
  2. While you are waiting for the solution to filter, write a balanced reaction for the experiment you are performing. Remember all lead compounds are precipitates. Then do problem numbers 3-7

CONCLUSIONS AND QUESTIONS

How many grams of precipitate should you make?

What is another name for a double replacement reaction?

Give a brief general description of a double replacement reaction. What must one of the products of such a reaction be in order to perform an experiment such as this one?

Suggest some possible sources of error in this experiment

Define the terms filtrate, and precipitate and limiting reactant, and excess reactant.

Determine a percent error based on the grams of PbI2 you should have produced and how much you did produce. Define theoretical yield and actual yield.