Inorganic practical- testing for anions and cations

Question 1

How to test for group 2 ions

Answer 1

1. Put 4 test tubes in a rack
2. Add 10 drops of 0.1 moldm^-3 metal chloride (group 2 metal)
3. Add 10 drops of dilute sodium hydroxide and swirl the test tube
4. Continue to add sodium hydroxide until its in excess
   Repeat this for each group 2 metal chloride and record results in a table
   Repeat using ammonia solution, sulfuric acid solution

Question 2

Mg and ammonium solution result

Answer 2

white precipitate

Question 3

Mg and sodium hydroxide result

Answer 3

white precipitate

Question 4

Mg and sulfuric acid result

Answer 4

colourless solution

Question 5

Ca and ammonium solution

Answer 5

no change

Question 6

Ca and sodium hydroxide

Answer 6

white precipitate

Question 7

Ca and sulfuric acid

Answer 7

slight white precipitate

Question 8

Sr and ammonium solution

Answer 8

no visible change

Question 9

Sr and sulfuric acid

Answer 9

white precipitate

Question 10

Sr and sodium hydroxide

Answer 10

slight white precipitate

Question 11

Ba and ammonium solution

Answer 11

no change visible

Question 12

Ba and sodium hydroxide

Answer 12

no change

Question 13

Ba and sulfuric acid

Answer 13

white precipitate

Question 14

How to test for ammonium ions

Answer 14

1. Add 10 drops of a solution containing ammonium ions to a test tube
2. Add 10 drops of sodium hydroxide using a pipette
3. Swirl the test tube to mix
4. Place the test tube in a water bath heated over a bunsen
5. Use a pair of tongs to hold a damp piece of red litmus paper near the mouth of the test tube

Question 15

Positive result for ammonium ions

Answer 15

damp red litmus paper will turn blue

Question 16

How to test for halide ions- making precipitate

Answer 16

1. Add the sample being tested to a test tube using a pipette.
2. Add a small amount of nitric acid using a pipette, followed by a small amount of silver nitrate
3. A precipitate will form if a halide ion is present

Question 17

chloride ions and silver nitrate

Answer 17

white precipitate forms

Question 18

bromide ions and silver nitrate

Answer 18

cream precipitate forms

Question 19

iodide ions and silver nitrate

Answer 19

yellow precipitate forms

Question 20

AgCl and ammonia

Answer 20

Dissolves in dilute ammonia

Question 21

AgBr and ammonia

Answer 21

dissolves in concentrated ammonia

Question 22

AgI and ammonia

Answer 22

doesnt dissolve in ammonia

Question 23

How to test for hydroxide ions

Answer 23

1. Add a small amount of the solution to a test tube using a pipette
2. Test the pH using red litmus paper or universal indicator-

Question 24

positive result for hydroxide ions

Answer 24

Red litmus paper goes blue, universal indicator goes blue/purple

Question 25

How to test for carbonate ions

Answer 25

1. Add a small amount of dilute hydrochloric acid to a test tube using a pipette 2. Then add an equal amount of sodium carbonate using a clean pipette 3. As soon as the sodium carbonate is added, attach a bung with a delivery tube 4. The delivery tube is attached to a test tube with limewater in it

Question 26

Positive result for carbonate ions

Answer 26

limewater goes cloudy

Question 27

How to test for sulfate ions

Answer 27

1. Acidify the solution using dilute HCl 2. Add a few drops of barium chloride

Question 28

Positive result for test for sulfate ions

Answer 28

White precipitate forms,(Barium sulfate)