UNIT-Atomically Correct
Laboratory 1 – Chemical Equations
Determining the Formula of a Compound
In this experiment, you will determine the relationship between the number of moles of copper and the
number of moles of silver involved in a chemical reaction. You will find the mass of a sample of solid silver
nitrate and prepare a water solution of it. You will also find the mass of a piece of copper wire, place it in
solution, and observe its behavior. By finding the mass of the copper wire at the close of the experiment, you
will be able to investigate quantitatively any changes that occur.
Procedure
Day 1
1. Obtain a piece of heavy copper wire. Straighten out the wire with your hands as well as possible.
Starting at one end, wrap a piece of fine copper wire around the heavy wire to within 4 or 5 cm of the other
end. Start by putting a tight loop around the end, then a loose spiral for about 4 cm, another tight loop, then a
loose spiral, and so on. Place the wire assembly in a labeled paper towel in the cabinet under your lab station.
2. Label and weigh a clean-dry 100-mL beaker. Record this mass in your data table.
3. CAUTION: SILVER NITRATE, SOLID OR SOLUTION, REACTS WITH SKIN AND TURNS IT BLACK. BE
CAREFUL TO AVOID SPILLING ANY ON YOUR SKIN OR CLOTHING.
Find the mass of a plastic tray and record. With the plastic tray on the balance add 3.00 g of silver
nitrate (AgNO3). Add the 3.00 g of AgNO3 to the 100-mL beaker. Since we want all 3.00 g of the AgNO3 in
solution, you should rinse the plastic tray with a small squirt of distilled water from your wash bottle.
4. Put about 10 mL of distilled water into the labeled 100-mL beaker to dissolve the AgNO3. Cover the
beaker with Parafilm and place in the cabinet under your lab station with your copper wire assembly.
DAY 2
5. Sand the copper wire. Find the mass of the wire assembly and record in your data section.
to a
tube.
6. Pour the silver nitrate solution into a 20 x 150 mm test tube that is held by a utility clamp attached
ring stand. Rinse out the beaker with two 5-mL portions of distilled water. Add the rinses to the test
7. Put the wire assembly into the test tube. Make sure it is centered at the bottom. For several minutes
observe any changes that take place. Let the assembly stand for at about 30 minutes.
8. Meanwhile, determine the mass of a piece of filter paper to the nearest 0.01 g. After folding the
paper, fit it into a funnel and moisten it with some distilled water from a wash bottle.
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9. At the end of the 30 minutes, shake the crystals off the wire into the test tube. Use your wash bottle
to rinse onto the filter paper any crystals that tend to stick to the wire. Set the wire in the labeled paper towel
to dry.
10. Pour the contents of the test tube into the filter. Collect the filtrate in a 250-mL beaker, not the one
you used in step 2, you will need that later. Now use your wash bottle to rinse out any particles of silver that
may have been left behind in the test tube. Wash the silver in the funnel thoroughly with distilled water.
11. Set the filter paper cone with the silver into the labeled 100-mLbeaker and put in the drying oven.
Day 3
12. Allow the beaker containing the filter paper and silver to cool before determining its mass. Record
the mass. Place the beaker and its contents back in the oven to weigh again on the next day. Find the mass of
the copper wire. Put it back under your station to weigh again the next day.
Calculations and Results
(Attach your answers to this section on a separate sheet of paper with your data table.)
SHOW WORK. ALL NUMBERS SHOULD BE LABELED AS TO WHAT THEY MEASURE AND HAVE UNITS.
1. Calculate the mass of copper metal used up in the reaction.
2. Calculate the number of moles of copper metal that reacted.
3. Calculate the mass of silver metal produced in this reaction.
4. Calculate the number of moles of silver produced.
5. Determine the ratio of moles Ag/ 1 mole Cu. Express your answer as a decimal to 2 significant figures.
6. Using class data for the ratio of moles Ag/ 1mole Cu, calculate:
(a) outliers - Ignore these outliers in the rest of your calculations.
(b) mean
(c) median
(d) Q1 & Q3
7. Using the class data for the ratio of moles Ag/ 1mole Cu, write a balanced chemical equation that
represents how the atoms rearrange in this chemical change.
8. How would the following errors affect the ratio of moles Ag/ moles Cu you experimentally determined-- too
low or too high? Explain your answer.
(a) The silver metal (Ag) produced is not dry when weighed.
(b) After the reaction is complete, a piece of the copper wire assembly breaks off as it is being
transferred to the paper towel to dry.
9. What is the chemical formula for the substance that causes the blue color in the solution after the reaction
is completed?
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