Experiment #4 Mole Relationships In A Chemical Reaction
In a chemical reaction, the reactants interact to form new products. Is there a relationship between the number
of moles of reactants that interact and the balanced equation for the reaction? In this lab you will try to answer this
question by reacting copper metal with silver nitrate to produce silver crystals. You will determine the mole ratio of
copper to silver and compare this with the balanced equation.
Procedure
1. Measure 0.75 grams of silver nitrate (AgNO3 ) and place in a test tube that has been cleaned and rinsed with
distilled water.
2. Add some distilled water and shake to dissolve the crystals. Then add enough distilled water so that the test
tube is full up to 2cm from the top. Stopper and shake to mix the solution. Then write the number of your lab
station on the test tube and place it in the test tube rack to save.
3. At the start of the class period the next day obtain your test tube, a one-hole stopper, piece of filter paper and
also a piece of copper wire. Measure and record the mass of the copper wire and filter paper separately.
4. Place the one-hole stopper in the test tube. Place the copper wire through the hole and bend one end over the
edge of the stopper so that the wire is suspended through the stopper and the solution covers as much of the
wire as possible.
5. Set the test tube in the test tube rack for support. Make some initial observations after 2-3 minutes then sit
down. Let it react for 30 minutes. (From time to time, gently shake the crystals from the wire into the test tube.)
6. After 30 minutes examine the test tube and wire and record your observations of what has happened. Gently
shake the crystals from the wire into the test tube. Be sure to save all crystals.
7. Collect the crystals by filtering. Rinse all crystals into the filter paper. Rinse any crystals on the copper wire into
the filter paper. Rinse the crystals with distilled water.
8. Carefully remove the filter paper with crystals from the funnel and place on a watch glass to dry. Place the
copper wire on the filter paper and leave overnight to dry.
9. The next day measure the mass of the copper wire and record. Recycle the wire. Measure the mass of the silver
crystals with filter paper and record. Return the silver “waste” to the designated container.
Lab Calculations
1. Determine the mass (and moles) of the copper wire that reacted. Determine the mass (and moles) of the silver
crystals that were produced.
2. Find the ratio of moles of silver to moles of copper and round off to the nearest whole number.
3. Write a balanced equation for the single replacement reaction for copper metal with silver nitrate solution. The
copper compound produced has the copper with the 2+ ion charge.
4. Examine the coefficient s for the copper and silver in the balanced equations. How does the ratio of copper used
in the equation to silver produced compare to your mole ratio from the lab?
5. Convert the 0.75 grams of silver nitrate you used in the lab to moles. What is the ratio of moles of silver nitrate
used to moles of silver produced? Is the mole ratio of moles of silver nitrate to silver moles the same as in the
balanced equations?
6. How many atoms of silver were produced in your lab? How many atoms of copper reacted? What is the ratio of
the two? How does this compare to the ratio from the balanced equation?
7. Write a formal conclusion. (Be sure to address the relationship between balanced equations and mole ratios of
reactants and products.)