Testing for ions and gases

Question 1

Test for hydrogen gas

Answer 1

A lit splint will make a squeaky pop

Question 2

Test for oxygen gas

Answer 2

A glowing splint/taper relights

Question 3

Test for Carbon Dioxide gas

Answer 3

Limewater turns milky/cloudy

Question 4

Test for sulphate

Answer 4

Add a few drops of nitric acid to a sample

Add a few drops of barium chloride or barium nitrate

Question 5

Result for sulphates

Answer 5

White ppt

Question 6

Test for halide ions

Answer 6

Add a few drops of nitric acid (HNO3)
| Add a few drops of silver I nitrate (AgNO3)

Question 7

Result for Cl-

Answer 7

White ppt

Question 8

Why is needed nitric acid?

Answer 8

To remove impurities

Question 9

Result for Br-

Answer 9

Cream ppt

Question 10

Result for Iodine ( I-)

Answer 10

Yellow ppt

Question 11

Test for Carbonate ions

Answer 11

Put some acid into a boiling tube with a side arm
Add a spatula of material to be tested
Bubble any gas into limewater

Question 12

Result for Carbonate ions

Answer 12

If it is a carbonate, limewater will change from colourless to cloudy/milky

Question 13

Test for metal ions in a solution

Answer 13

Put a small amount of solution in a test tube

Add a few drops of sodium hydroxide (NaOH)

Question 14

Result for metal ions in a solution

Answer 14

Cu2⁺ - blue ppt
Fe2⁺ - green ppt
Fe3⁺ orange/brown ppt

Question 15

Test for solid metal ions

Answer 15

1) Clean a nichrome or platinum wire loop
2) Pick up some of the solid powder that you want to test
3) Put the wire loop with the powder into the non-luminous part of the Bunsen flame
4) Observe the colour

Question 16

How do you clean a nichrome or platinum wire?

Answer 16

Dip it into concentrated HCl and heat it in a hot Bunsen flame

Question 17

Result for Li⁺

Answer 17

Red

Question 18

Result for Na⁺

Answer 18

Orange

Question 19

Result for K⁺

Answer 19

Lilac

Question 20

Result for Ca2⁺

Answer 20

brick red

Question 21

Result for Cu2⁺

Answer 21

blue / green

Question 22

Test for ammonium ions (NH₄⁺)

Answer 22

Add a sodium hydroxide soluition

if it is NH₄⁺, produce a gas - NH3 (ammonia)

Question 23

Result for ammonium ions

Answer 23

Ammonia is an alkaline gas

damp red litmus paper will turn blue

Question 24

Test for chlorine gas

Answer 24

Use a damp blue litmus paper

Question 25

Result for chlorine gas

Answer 25

Turns red | Then bleaches the paper white

Question 26

Test for water

Answer 26

Add some anhydorous copper II sulfate

Question 27

Result for water

Answer 27

See colour change from white to blue

Question 28

Test for pure water

Answer 28

Heat it up, "if" it boils at 100°C, it is pure water | Cool it down, "if" it freezes at 0°C, it is pure water

Question 29

What can't you say for test for pure water?

Answer 29

You CAN'T say "boil at 100°C" because you CAN'T control that