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Chemistry/Redox

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Chemistry 12
REDOX LAB


DATA

Table 1 Solution A Solution B Solution C Solution D Solution E
metal A X
metal B X
metal C X
metal D X
metal E X


Table 2 X– Y– Z– Pet Ether
X2 X
Y2 X
Z2 X


PROCEDURE
1. Obtain strips of each of the 5 different metals. Use the table below to keep the metals properly identified. If the metal strips are dirty or corroded, polish them with a piece of emery cloth.

Metal Appearance / Behaviour
A thin, springy
B somewhat thick, heavy, NOT springy (droops), bends easily
C thick, slight yellowish or pinkish tinge, heavy, resists bending
D very narrow strip, thin, springy
E somewhat thick, red–brown, heavy, resists bending


2. Obtain for your bench one bottle of each of solutions A, B, C, D, E, X2 , Y2 , Z2 , X–, Y– and Z–.


3. Pour about 2 mL (3 cm height) of solution A into each of 4 clean and flicked–dry small test tubes and arrange in a test tube rack. Into the 1st tube place a strip of metal B, into the 2nd tube place metal C, into the 3rd tube place metal D and into the 4th tube place metal E.


4. If a reaction is seen, place the word “REACTS” in the appropriate place in Table 1. If no reaction is seen after 3 minutes, place a dash “—” in the table to indicate no reaction occurs. As soon as you are through with a solution, discard the liquid down the sink, wash off the metal without touching the solution, and dry the metal. If necessary, use emery cloth to clean the metal strips again.


5. Pour about 2 mL of solution B into each of 4 clean and flicked–dry small test tubes and arrange in a test tube rack. Into the 1st tube place a strip of metal A, into the 2nd tube place metal C, into the 3rd tube place metal D and into the 4th tube place metal E. Repeat procedure step 4 to record the reactions seen.


6. Repeat steps 3 and 4 for solutions C, D and E.


7. Pour 2 mL of petroleum ether into each of 3 clean, flicked–dry test tubes. Into the 1st tube add t 1 mL of X2 , stopper the tube and shake for 5 s. Record the colour of the upper petroleum ether layer in the last column of Table 2. Into the 2nd tube add 1 mL of Y2 , stopper the tube and shake for 5 s. Record the colour of the upper petroleum ether layer. Into the 3rd tube add a1 mL of Z2 , stopper the tube and shake for 5 s. Record the colour of the upper petroleum ether layer.


8. Pour 1 mL of X2 and 2 mL of petroleum ether into each of two clean, flicked–dry test tubes. Add 2 mL of Y– to the 1st test tube. Stopper the tube and shake well for 5 s. Record the colour of the upper petroleum ether layer in Table 2. Add 2 mL of Z– to the 2nd test tube. Stopper the tube and shake well for 5 s. Record the colour of the upper petroleum ether.


9. Pour 1 mL of Y2 and 2 mL of petroleum ether into each of two test tubes. Add 2 mL of X– to the 1st test tube. Stopper the tube and shake well for 5 s. Record the colour of the upper petroleum ether layer in Table 2. Add 2 mL of Z– to the 2nd tube. Stopper the tube and shake well for 5 s. Record the colour of the upper petroleum ether layer.


10. Pour 1 mL of Z2 and 2 mL of petroleum ether into each of two test tubes. Add 2 mL of X– to the 1st test tube. Stopper the tube and shake well for 5 s. Record the colour of the upper petroleum ether layer in Table 2. Add 2 mL of Y– to the 2nd tube. Stopper the tube and shake well for 5 s. Record the colour of the upper petroleum ether layer.


ANALYSIS
1. Examine Table 2. If the colour of the petroleum ether layer for the reaction mixture involving X2 and Y– is the same as the colour of X2 in petroleum ether recorded in the last column of Table 2, you can conclude that X2 DID NOT REACT to form a different substance. In this case, place a dash, “—”, in the table below. However, if the colour of the petroleum ether layer in the reaction is DIFFERENT from the colour of X2 recorded in the last column, you can conclude that a reaction DID occur. Complete the entire table below.


X– Y– Z–
X2 X
Y2 X
Z2 X


2. The metal ion/metal reduction reactions can be written as A2+(aq) + 2 e– <===> A(s). List the reduction reactions for A2+, B2+, C2+, D2+ and E2+ from greatest tendency to reduce to least tendency.


3. The halogen/halide ion reduction reactions can be written as X2(aq) + 2 e– <===> 2 X–(aq). List the reduction reactions for X2 , Y2 and Z2 from greatest tendency to reduce to least tendency.


4. One of the metal ions used can oxidize only one of the halide ions. None of the other metal ions can oxidize any of the halide ions. Combine all the reduction reactions in this experiment into one list, ranked from greatest to least tendency to reduce.


5. Write complete redox reactions showing how X–, Y– and Z– individually react with X2 , Y2 and Z2 . Only list combinations that actually react.


6. In the early 1900's, the drains of sinks in chemical laboratories used to be made of lead metal. Would disposal of Zn2+ solutions cause a problem with such sinks? Explain your answer. Would disposal of Cu2+ solutions cause a problem? Explain.


7. As the manager of a swimming pool which sterilizes the water by dissolving Cl2 into the water, what advice would you have for patrons that wish to wear silver rings in the pool? Explain the chemistry behind your advice. What advice would you have for patrons that wished to wear copper rings? Gold rings? Explain.

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