Transcript 25.1 Disposing of toxic heavy metals

25.1 DISPOSING
OF TOXIC
HEAVY METALS
PRE-LAB: PART A- “FIXING” THE COPPER
IONS IN A SOLID MIXTURE
LESSON TARGETS
• I can understand that many useful
chemical processes produce waste
by-products that must be disposed
of safely.
• I can experiment with different
products to find the best method to
solidify and safely dispose of the
liquid waste produced during the
refining process.
VOCABULARY
Leach- the removal of a substance by
the filtering of water or other liquid
(ex. Rainwater can leach minerals and
fertilizers from soil.)
Heavy metals- metal of relatively high
density, or of high relative atomic
weight. Excessive levels of exposure
can be damaging to humans.
TESTABLE QUESTION
How does the fixing of copper sulfate in
different concentrations of cement or
sodium silicate affect the leaching of
copper from the solid material?
Note: We want the copper to stay in the
solid material. This would mean we are
keeping it out of the soil and water…
HYPOTHESIS
Write a hypothesis for what you believe will
happen with the copper when it is fixed into
a solid material.
If the copper sulfate is combined with
______________ then it will _____________,
because______________________.
MATERIALS
List the materials you will use in Part A make sure your list is
bulleted.
• 180mL bottle of sodium silicate
• Portland cement
• 120mL dropper bottle of 50,000ppm copper sulfate sln.
• Clear plastic cup
• Plastic spoon
• 30mL graduated cup
• Safety glasses
• Paper towels
SAFETY NOTE
Portland cement can irritate your
eyes and lungs. Do not breathe in
the mixture and wear your
goggles.
Sodium silicate is a skin irritant;
wash thoroughly if it comes in
contact with your skin.
VARIABLES
•
Manipulated Variable: Ratio of
cement to sodium silicate
•
Responding Variable: The
concentration of copper
sulfate
•
Control Variables: Amount of
copper sulfate; time to solidify
PROCEDURES PART A
1. Pour measured amount of Portland cement into the clear
plastic cup. Use a paper towel to wipe out any dry
cement that clings to the side of the cup.
2. Add 10mL of 50,000ppm copper sulfate sln. to the
cement in the plastic cup. Stir to combine. Rinse the
graduated cup.
3. Use the graduated cup to add the assigned amount of
sodium silicate to the copper-cement mixture. Mix well.
Record description of mixture in data table.
4. Label cup with period and group number.
5. Place in fume hood to dry overnight.
DATA TABLE
Check with other groups and fill in
the information for the
“Appearance of Mixture”.
Look in the Fume Hood to see the
dry mixtures.
PART B LESSON
TARGET
I can calculate the
concentration of a waste
solution based on the
concentration of a known
solution.
PART B.
CONTNTINUED
1. Add 10 drops of your teams copper sulfate sln. to Cup 1
2. Add 9 drops of water to Cups 2- 5, and 10 drops of water
to Cup 6.
3. Transfer one drop of sln from Cup 1 to Cup2.
4. Continue dilution procedure adding one drop of the
previous sln. to the next cup up to Cup 5.
5. Record the color of each cup in your data table.
6. Add 10 drops of ammonia to all 6 cups.
7. Record observations.
SERIAL DILUTION
PART B
50,000ppm Sln.
OR
24.1 Waste Sln.
PART B. ANALYSIS
QUESTIONS
1. How does the addition of ammonia help determine the
concentration of copper in a solution? Is it necessary?
2. What is the lowest concentration of copper that can be
detected using the ammonia test?
3. Compare your groups estimate of the concentration of
copper in the undiluted waste solution from activity 24.1
(Part A, Procedure step 9) with the estimate made by
another team. How close are the two estimates? Explain
reasons you see for any variations. What do you think
you should do if the variations are large?
PART B. ANALYSIS
QUESTIONS
4. An independent laboratory performed the same test as
Team A on a 50,000ppm copper sulfate solution. They
report the data in the table shown below. Describe the
similarities and differences between their results and
those your group reported.
EXPERIMENTAL SET UPBEFORE ADDITION OF
AMMONIA
RESULTS
These circles
represent the
experimental
controls – Water
and ammonia.
RESULTS
What do the
results suggest?
PART C TESTING YOUR
SOLIDIFIED MIXTURE UNDER
ACIDIC CONDITIONS
Lesson Target
I can determine if
solidifying heavy metals in
a solid matrix stops them
from leaching into the
surrounding environment.
PROCEDURES
1.
Pick up a 5ml crushed sample of the solid you prepared in
Part A.
2.
Prepare a Filter set up- wetting the filter paper to help it sit
in the funnel.
3.
Add 10mL of simulated acid-rain solution to the crushed
solid in your cup. Swirl for 30 seconds.
4.
Transfer the contents of the cup to the filter set up and clean
the cup.
5.
Using the data table from Part A record the color of the
filtrate collected in the large cup.
6.
Transfer 10 drops of filtrate to Cup 1 of your tray, add 10
drops of 5% ammonia to it. Record the color in your table.
7.
Estimate the copper concentration. Record in your table.
8.
Complete your data table by checking with other groups.
ANALYSIS QUESTIONS
Answer analysis Questions 1-5 in your lab notebook.
1.