Exp 9

Question 1

Exp 9:
1. Place __ drops each of the ff aqueous solutions to separate centrifuge tubes: 1M Ba(NO3)2, 1M Mg(NO3)2, 1M Ca(NO3)2, and 1M Sr(NO3)2. Make each solution basic by adding a few drops of _____. Confirm using filter paper

Answer 1

• 20
• 6M NH4OH

Question 2

Exp 9:
2. Carefully add 1mL _____, and stir. Put the centrifuge tube into hot (but not boiling) water and leave in the water bath for ___ minutes. Stir occasionally.

Answer 2

• 1M (NH4)2CO3
• 2

Question 3

Exp 9:
3. Centrifuge and decant the supernatant liquid into ______

Answer 3

another centrifuge tube

Question 4

Exp 9:
4. To the test tube containing Ba2+, wash the precipitate with ____. Centrifuge out the precipitate and discard the wash

Answer 4

2mL water

Question 5

Exp 9:
5. Add _____ to the precipitate in step 4 and stir to dissolve the remaining solid residues

Answer 5

0.5 mL 6M acetic acid

Question 6

Exp 9:
6. To confirm the presence of Ba2+, add _____ of water and 5 drops of ___ and mix. Then add 0.5 mL _______

Answer 6

• 1 mL
• 6M NH3
• 1M K2CrO4

Question 7

Exp 9:
7. To the remaining test tubes, add ______ until the solution is basic. Stir thoroughly to ensure that the entire sample is basic

Answer 7

6M NH3

Question 8

Exp 9:
8. To confirm the presence of Sr2+, add _________

Answer 8

1mL of saturated CaSO4 solution

Question 9

Exp 9:
9. To confirm the presence of Ca2+, add ______ and mix well

Answer 9

0.5 mL 1M K2C2O4

Question 10

Exp 9:
10. To confirm the presence of Mg2+, add 0.5 mL ________ and mix well. Stir the solution, warm it gently in the hot water bath, and let it stand for a minute

Answer 10

• 1M Na2HPO4