Exp 8

Question 1

Exp 8:
1. Place ___ of each of the ff aqueous solutions to separate centrifuge tubes: 0.1 M Ct(NO3)3, 0.1M Al(NO3)3, 0.1M Co(NO3)2, 0.1M Zn(NO3)2, 0.1M Mn(OH)2, 0.1M Ni(NO3)2, 0.1M Fe(NO3)3. Make each solution basic by adding __ mL of ____. Confirm using a ______

Answer 1

• 1mL
• 2 mL
• 6M NaOH
• litmus paper

Question 2

Exp 8:
2. Add ____ drops of fresh ___ and slowly stir for 1 minute. Then, worm in the hot bath for ____. Record your observation

Answer 2

• 15 - 18 drops
• 3% H2O2
• 5 minutes

Question 3

Exp 8:
3. After heating the mixtures, add __ drops of ____. Boil the mixture again for another ___ minutes. After, let it cool and centrifuge. If solid residues are formed, discard the supernatant liquid. For those with tubes with no solid residues, save the supernatant liquid for further analysis

Answer 3

• 16
• 6M NH3
• 2

Question 4

Exp 8:
4. To the centrifuge tube containing Al3+, Zn2+ and Cr3+, slowly add few drops of ______ to solution until it is acidic (test with ____ litmus paper). After, add _____ one drop at a time until the solution just becomes basic again (test with red litmus paper). Then, add additional drops of excess __. Stir the mixture for about a minute to allow the system to reach equilibrium. Warm the mixtures in a water bath for ___ minutes. Decant the supernatant liquid if there is a precipitate produced.

Answer 4

• 6M acetic acid
• blue
• concentrated NH3
• NH3
• 5

Question 5

Exp 8:
5. To the precipitate containing Al3+, wash the collected solid with ________. Then, place the tube in a hot water bath for about ___ mins occasionally stirring the mixture. After, decant the supernatant solution and save the precipitate. To the precipitate, add 4 drops of _______ and _____ mL of DI water. Stir in order to dissolve the solid. Finally, add four drops of _______ to the resulting solution

Answer 5

• 6mL DI water
• 2
• 6M CH3COOH
• 6
• catechol violet

Question 6

Exp 8:
6. To the centrifuge tube containing Cr3+, add twelve drops of _____ and observe

Answer 6

1M BaCl2

Question 7

Exp 8:
7. To the solution containing Zn2+, acidify with a few drops of ______ and add 3 - 5 drops of ______

Answer 7

• 6M CH3COOH
• (NH4)2S

Question 8

Exp 8:
8. To the remaining precipitates obtained from procedure 3 that contain Fe+3, Mn+2, Ni+2, and Co+2, wash the precipitate with hot ____ and discard the liquid. To the precipitates, add 10 drops of _____ and 4 drops of _____. Mix well and heat in the water bath until the precipitate dissolves as much as possible. After the water bath, add _____ dropwise until the solution is ____. Use red litmus paper to confirm. Centrifuge and decant the supernatant liquid

Answer 8

• DI water
• 6M HCl
• HNO3
• Conc. NH3
• basic

Question 9

Exp 8:
9. To the solution containing Ni+2, add ____ or _____ to make the solution alkaline and add 8 drops of ______ (DMG).

Answer 9

• NH4OH or NH4Cl
• dimethyglyoxime

Question 10

Exp 8:
10. To the solution containing Co2+, acidify by adding a few drops of ________ and 10 drops of _____. Without mixing, add _____ to form a layer on top.

Answer 10

• 6M Ch3COOH
• 1.0M KSCN solution
• 1 mL of acetone

Question 11

Exp 8:
11. To the precipitate containing Fe+3, add 12 drops of ____ and __ mL of DI water. Stir the solution until the precipitate dissolves and add a few drops of ______

Answer 11

• 6M HCl
• 1
• 1.0 M KSCN solution

Question 12

Exp 8:
12. To the precipitate containing Mn 2+, add 12 drops of _____ and ______. Warm the mixture and then, add a pinch of ____ powder.

Answer 12

• conc. HNO3
• 5 drops of DI water
• NaBiO3