Anachem Experiment 1

Question 1

What are the 3 steps involved in the procedure?

Answer 1

1. The group is precipitated with dilute HCl (hydrochloric acid) as insoluble chlorides
2. Lead chloride (PbCl2) is removed from the precipitate by leaching with hot water
3. Separation of AgCl from Hg2Cl2 with ammonia water

Question 2

What Group I cations are included in the activity

Answer 2

silver, lead, and mercurous ions (absent Hg2+)

Question 3

How do you test for the presence of the three ions?

Answer 3

Unknown sample–transfer in a test tube (+10 drops 3M HCl)–Mix then centrifugate (Speed of 2; 1 Minute)– Test for complete precipitation (+ 1 drop of 3M HCl)–Residue Wash with 10 drops of water + 1 drop of 3M HCl– stir centrifugate–white precipitate (may contain ions).

Question 4

What does it mean after centrifugation the sample is still cloudy?

Answer 4

precipitation is not complete

Question 5

After centrifugation (supernatant liquid), what will happen to the centrifugate?

Answer 5

The Supernatant liquid is discarded into another test tube

Question 6

The Supernatant liquid is discarded into another test tube, what lab equipment is used?

Answer 6

Pipette/ Dropper

Question 7

Unknown sample–transfer in a test tube (+10 drops 3M HCl)–Mix then centrifugate (Speed of 2; 1 Minute)– Test for complete precipitation (+ 1 drop of 3M HCl)–Residue Wash with 10 drops of water + 1 drop of 3M HCl– stir centrifugate–white precipitate. It may contain __________.

Answer 7

PbCl2, AgCl, Hg2Cl2

Question 8

What solution is used in finding the presence of lead ions (Pb2+)?

Answer 8

4 drops of 1 M K2 CrO4 (Potassium Chromate)

Question 9

What solution is used in separating Mercurous ions and Silver Ions?

Answer 9

ammonia water (NH4OH)

Question 10

In testing for the presence of mercurous ions (Hg2+), what is the color of the precipitate/ residue?

Answer 10

black (blackens)

Question 11

In testing for the presence of silver ions (Ag+), what is the color of the precipitate/ residue?

Answer 11

white ppt

Question 12

What solution is used to check the acidity of the centrifugate

Answer 12

1 drop of 3M HNO3

Question 13

If blue litmus paper turns to red, centrifugate is___________.

Answer 13

acidic

Question 14

Chemical Formula of Silver ions

Answer 14

Ag+

Question 15

Chemical Formula of lead ions

Answer 15

Pb^2+

Question 16

Chemical Formula of mercurous ions

Answer 16

Hg2^2+

Question 17

Group 1 cations are precipitated in their _____ forms

Answer 17

Chloride forms

Question 18

what is the precipitating reagent

Answer 18

HCL - Hydrochloric Acid

Question 19

What are the 3 insoluble chlorides

Answer 19

Silver chloride
Mercurous chloride
Lead chloride

Question 20

Chemical formula of Silver chloride

Answer 20

AgCl

Question 21

Chemical formula of Lead chloride

Answer 21

PbCl2

Question 22

Chemical formula of Mercurous chloride

Answer 22

Hg2Cl2

Question 23

Precipitate of lead ions

Answer 23

yellow

Question 24

Precipitate of SIlver ions

Answer 24

white

Question 25

Precipitate of Mercurous ions

Answer 25

Black, Gray, or White

Question 26

What is added to the centrifugate to test for lead ions?

Answer 26

4 drops of K2 CrO4 (POTASSIUM CHROMATE)

Question 27

What is added to the residue to test for mercurous ions?

Answer 27

10 drops 3M NH4OH (Ammonia)

Question 28

What is added to the centrifugate to make it acidic?

Answer 28

3M HNO3 (Nitric Acid)

Question 29

What is added to dissolve precipitate

Answer 29

2 drops of conc. HNO3 (Nitric Acid)

Question 30

Produces white or gray precipitate

Answer 30

SnCl2 solution

Question 31

first test for mercurous ions

Answer 31

10 drops 3M NH4OH

Question 32

2nd test for mercurous ions

Answer 32

1-2 drops of SnCl2 solution

Question 33

lead chloride is removed from the precipitate by leaching with ________

Answer 33

hot water

Question 34

What separates AgCl from Hg2Cl2

Answer 34

ammonia water