Lab-Reactions of Fe2+ and Fe3+ Ions
Purpose:
-Observe the properties and reactions of the Fe2+ and Fe3+ ions
-Determine which ion, Fe2+or Fe3+, is present after a chemical reaction
Materials:
0.1 M Fe(NH4)2(SO4)2 3 M HCl
0.1 M FeCl3 1 M H2SO4
0.1 M K4(Fe(CN)6) 3% H2O2
0.1 M K3Fe(CN)6) Mg ribbon
2 test tubes deionized water
test tube brush
Safety:
-wear goggles
-H2SO4 and HCl are corrosive. Avoid contact with skin and eyes. Wash hands thoroughly before leaving the lab.
Pre-Lab:
A brand new element, Xx, is discovered and found to have a variable charge of 1+ and 2+. When treated with chemical A, the source of Xx+ turns green and the source of Xx2+ turns red. Two test tubes are labeled A and B. Ten drops of the source of Xx+ is placed in test tube A and ten drops of the source of Xx2+ is placed in test tube B. Both test tubes are sent through a series of reactions with the addition of various reagents. For the final step, three drops of chemical A is added. Both of the solutions in the test tubes turn red. Determine the before and after charges of Xx in test tube A and test tube B.
Procedure:
Part A-Reactions of the Fe2+ Ion
1. Place 10 drops of 0.1 M Fe(NH4)2(SO4)2in 2 different test tubes.
2. To the first test tube, add 2 drops of 0.1 M K4(Fe(CN)6). Gently mix the contents in the test tube.
3. To the second test tube, add 2 drops of 0.1 M K3(Fe(CN)6). Gently mix the contents in the test tube.
4. Dispose of the materials in the test tubes in the appropriate waste container.
5. Clean the test tubes thoroughly and do a final rinse with deionized water to remove any residue.
Part B-Reactions of the Fe3+ Ion
6. Place 10 drops of 0.1 M FeCl3 in 2 different test tubes.
7. Repeat Steps 2-5 in Part A.
Part C-Treatment of Fe2+ and Fe3+with HCl and Mg
8. Place 10 drops of 0.1 M Fe(NH4)2(SO4)2 in a test tube.
9. Place 10 drops of 0.1 M FeCl3 in a test tube.
10. Add 10 drops of 3 M HCl and a strip of magnesium ribbon to each test tube.
11. Allow the reaction to continue until the strip of magnesium ribbon is completely consumed.
12. When the reaction is complete, add 2 drops of 0.1 M K3Fe(CN)6) to each test tube and gently mix.
13. Repeat Steps 4-5 in Part A.
Part D-Treatment of Fe2+ and Fe3+with H2SO4 and H2O2
14. Repeat steps 8 and 9 in Part C.
15. Add 2 drops of 1 M H2SO4 and 5 drops 3% H2O2 to each test tube
16. Gently mix each test tube for approximately 1 minute.
17. Add 2 drops of 0.1 M K4(Fe(CN)6) to each test tube and gently mix.
18. Repeat Steps 4-5 in Part A.
Data and Results:
Copy the following tables into your lab book and from your observations, record the color changes that occurred during the reactions.
Table I-Reactions of the Fe2+ ion
Fe(CN)64- / Fe(CN)63-Fe2+
Table II-Reactions of the Fe3+ Ion
Fe(CN)64- / Fe(CN)63-Fe3+
Testing to determine the charge of the iron ion after chemical treatment
Table III
Iron Ion Treated / Chemical Treatment / Ion Used in Testing / ResultStep 1 / Fe2+ / HCl and Mg
(Part C) / Fe(CN)63-
Step 2 / Fe3+ / HCl and Mg
(Part C) / Fe(CN)63-
Step 3 / Fe2+ / H2SO4 and H2O2
(Part D) / Fe(CN)64-
Step 4 / Fe3+ / H2SO4 and H2O2
(Part D) / Fe(CN)64-
Conclusion:
1. What is the difference in the reaction of the Fe2+ion and the Fe3+ion with the Fe(CN)64- ion?
2. What is the difference in the reaction of the Fe2+and the Fe3+ion with the Fe(CN)63- ion?
3. Using Table III, determine the charge of the iron ion before and after the chemical treatment.
a. Step 1 Before After
b. Step 2 Before After
c. Step 3 Before After
d. Step 4 Before After
4. Why would it be incorrect to name a compound composed of copper ions and chloride ions, copper chloride,
while it would be correct to name a compound composed of calcium ions and chloride ions, calcium chloride?