Sample Results:

Question

Mass (g)
Trial 1 Trial 2
Filter paper 1.36 1.29
Filter paper + PbI2 3.20 3.09
PbI2 ? ?
Calculations and Discussion Questions: ( show the step by step)

1. Calculate the mass of precipitate collected in Trial 1 and Trial 2. Include these values in your data table.
2. Calculate the average yield of precipitate in this experiment.
3. Calculate the theoretical yield of precipitate that was expected based on the initial concentration of the reactants. Note: Use the moles of KI when calculating the theoretical yield of precipitate possible, as potassium iodide is the limiting reactant.
4. Calculate the percentage yield of precipitate in this experiment.
5. State two reasons why the yield is below 100%.
6. State one way to improve upon the experimental technique that could increase the percentage yield.

Answer 1

In this investigation, you will study the reaction between lead(II) nitrate, Pb(NO3)2, and potassium iodide, KI, to determine the percentage yield of lead(II) iodide. This reaction occurs based on the following equation:

This image shows Pb(NO sub 3 ) sub 2(aq) + 2KI sub (aq), reaction arrow, Pbl sub 2(s) + 2KNO sub 3(aq).

Purpose:
To determine the percentage yield of lead(II) iodide precipitate produced in a reaction between lead(II) nitrate and potassium iodide.

Materials:
Chemicals:
1.0 mol/L lead(II) nitrate solution
1.0 mol/L potassium iodide solution

Apparatus:
pipettes (10 mL), pipette bulb, beaker (250 mL), Erlenmeyer flask (250 mL), funnel, filter paper, electronic balance, wash bottle with distilled water

Safety:
Safety goggles and lab aprons should always be worn when working with chemicals.

Procedure:
1. Use a pipette to measure 10.0 mL of the each of the two solutions and add to the beaker. Use a different pipette for each solution to avoid contaminating your stock solutions.
2. Swirl gently.
3. Determine the mass of the filter paper. An accurate measurement is very important.
4. Fold the filter paper in four and place it in the funnel supported by a flask.
5. Slowly pour the mixture into the funnel. Be careful not to overflow the filter paper. Use a wash bottle of distilled water to wash any remaining solid out of the beaker and onto the filter paper.
6. After filtering, let the paper dry overnight.
7. When it is completely dry, determine it's mass. Once again, accuracy is important. Be careful not to remove any of the solid product on the filter paper.
8. If time permits, repeat the entire procedure for a second time for accuracy.