HS CHEMISTRY Lead Compounds in Local Soils
Contributed by Katherine Mullane-Erlick
A. SAMPLING
Through testing soil samples (see field testing protocol below) from the local area, students
learn to use spot test for lead to test their environment.
Materials List:
3 plastic zip lock sandwich bags per student
1 plastic spoon
3 pieces of tape
Procedure:
Soil Samples:
You will take 3 soil samples.
One from your home
One from a friend or other family members home
One from another area of town, work or a place you go often.
Sample 1: Home
 Place a piece of tape on the outside of the bag to use as a label.
 Record the information for the sample on the label. Your name, date, soil source,
number for the pin for the class map.
 Find a place near the foundation of the building, record where outside of the building
you are taking the sample from bedroom, kitchen, bathroom, etc.
 Unzip the plastic bag. Open the bag wide as possible.
 Using the plastic spoon collect 3 teaspoons of soil from the location chosen.
 Re-zip the bag and carefully set it aside.
 CAUTION : Do Not place the plastic bag or the spoon on the ground this could
contaminate your sample. Place the sample into a box or shopping bag to keep it from
coming into contact with anything that could cause contamination.
Sample 2: Friend or other family home.
 Place a piece of tape on the outside of the bag to use as a label.
 Record the information for the sample on the label. Your name, date, soil source,
number for the pin for the class map.
 Find a place near the foundation of the building, record where outside of the building
you are taking the sample from bedroom, kitchen, bathroom, etc.
 Unzip the plastic bag. Open the bag wide as possible.
 Using the plastic spoon collect 3 teaspoons of soil from the location chosen.
 Re-zip the bag and carefully set it aside.
Sample 3: Work or other location
 Place a piece of tape on the outside of the bag to use as a label.
 Record the information for the sample on the label. Your name, date, soil source,
number for the pin for the class map.
 Find a place near the foundation of the building, record where outside of the building
you are taking the sample from bedroom, kitchen, bathroom, etc.
 Unzip the plastic bag. Open the bag wide as possible.
 Using the plastic spoon collect 3 teaspoons of soil from the location chosen.
 Re-zip the bag and carefully set it aside.
 CAUTION: Do Not place the plastic bag or the spoon on the ground this could
contaminate your sample. Place the sample into a box or shopping bag to keep it from
coming into contact with anything that could cause contamination.
Place all samples in a safe location and bring to class next time. Do not forget this will be one
lab grade.
B. LEAD PERCIPATE REACTION
Asarco refinery started operations in El Paso in 1887. The process of refining metals has the
ability to release harmful chemicals into the atmosphere. These chemicals move from the
atmosphere into the water and soil. Environmental concerns prompted the City of El Paso and
the State of Texas to keep the Asarco plant closed. There are other sources of Lead
contamination, including the use of Lead gasoline, Lead paint, and Lead solder in pipes. Many
health problems are related to exposure to Lead. The City of El Paso has had Soil testing
performed over all areas of the town and county. We are going to look at a qualitative test for
presence of Lead in the soil. We will then color in a city map with our findings.
Question: Do you think that the soil around your home will contain Lead? What area of El Paso
do you think would have the highest concentration of Lead in the soil?
Materials:
3 soil samples
Micro plates
Pipettes
Acetic Acid
Nitric Acid
Sulfuric Acid
Distilled water
Plastic Tweezers
Safety Equipment:
Goggles
Lab Apron
Disposable Gloves
Sodium Bicarbonate wash for spills
Testing Soil Samples:
You will work in groups of 2 for this activity.
 Make sure your soil samples are labeled with tape on the side of the plate or a piece of
paper under the micro plate. Do not confuse the samples from one student to the
next….Remember the samples look very much alike.
Student 1:
 Place the bag soil samples on the lab table.
 Unzip sample 1 and place ¼ teaspoon in the first well of the micro plate.
 Fill the pipette with distilled water.
 Transfer the distilled water to the soil sample in the first well of the micro plate.
 Let the soil sample sit and soak up the water while you set up your other soil samples.
 Repeat the process for Sample 2 in a separate well.
 Repeat the process for Sample 3 in a separate well.
Student 2:
 Place the bag soil samples on the lab table.
 Unzip sample 1 and place ¼ teaspoon in the first well of the micro plate.
 Fill the pipette with distilled water.
 Transfer the distilled water to the soil sample in the first well of the micro plate.
 Let the soil sample sit and soak up the water while you set up your other soil samples.
 Repeat the process for Sample 2 in a separate well.
 Repeat the process for Sample 3 in a separate well.
Control Sample:
 For each students soil sample set fill one additional well with distilled water.
 You will perform each of the acid test on the distilled water as you perform the test on
your soil samples.
Acetic Acid Test:
Student 1:
 Add the Acetic Acid wash to all of the soil samples and the control well.
 Carefully use the pipette to measure out 3 ml of Acetic Acid.
 Add the Acetic Acid to soil sample one.
 Repeat for Soil sample two and three and the control
Student 2:
 Add the Acetic Acid wash to all of the soil samples and the control well.
 Carefully use the pipette to measure out 3 ml of Acetic Acid.
 Add the Acetic Acid to soil sample one.
 Repeat for Soil sample two and three and the control
Nitric Acid Test:
Student 1:
 Add the Nitric Acid wash to all of the soil samples and the control well.
 Carefully use the pipette to measure out 3 ml of Nitric Acid.
 Add the Nitric Acid to soil sample one.
 Repeat for Soil sample two and three as well as the control
Student 2:
 Add the Nitric Acid wash to all of the soil samples and the control well.
 Carefully use the pipette to measure out 3 ml of Nitric Acid.
 Add the Nitric Acid to soil sample one.
 Repeat for Soil sample two and three as well as the control
Sulfuric Acid Test:
Student 1:
 Add the Sulfuric Acid wash to all of the soil samples and the control well.
 Carefully use the pipette to measure out 3 ml of Sulfuric Acid.
 Add the Sulfuric Acid to soil sample one.
 Repeat for Soil sample two and three as well as the control
Student 2:
 Add the Sulfuric Acid wash to all of the soil samples and the control well.
 Carefully use the pipette to measure out 3 ml of Sulfuric Acid.
 Add the Sulfuric Acid to soil sample one.
 Repeat for Soil sample two and three as well as the control
Observation and Data:


On the data sheet record your observations for each soil sample.
Include with your observations the description from the five descriptors below.

Observe each sample cell and record the presence or absence of any precipitate.
o Strong Reaction – visible white solid precipitate is formed- heavy lead presence
o Moderate Reaction – liquid is changed to solid and some white solid is visible –
moderate lead presence
o Weak Reaction – liquid is milky and small particles are visible – weak lead
presence
o Slight Reaction – Liquid is mostly clear with some light discoloration or small
solid matter floating in the liquid – very little lead presence
o No Reaction – No change in the liquid – No lead presence
Disposal of Chemicals:
Follow the teacher instructions for disposal and clean up of micro plates and lab station.
Carefully return all unused chemicals to the main lab station.
Class Data:
 Bring your data to the front board and record it for each of the three samples on the class
data sheet. Make sure you record you data next to the number for your map pin number.