Test for Gases

Question 1

How do you know hydrogen gas is evolved?

Answer 1

Lighted splint extinguished with a ‘pop’ sound.

Question 2

Name the four gases that have a pungent smell.

Answer 2

1. Ammonia gas; Colourless
2. Sulfur Dioxide gas; Colourless
3. Hydrogen Chloride gas; Colourless
4. Chlorine gas; Pale yellowish green

Question 3

Describe the test for oxygen.

Answer 3

1. Light a splint
2. Extinguish the flame
3. Place the glowing splint at the mouth of the test tube
4. Glowing splint should rekindle

Question 4

What colour is the ppt. that carbon dioxide forms with limewater?

Answer 4

White ppt.
Blue litmus paper turns red

Question 5

Which test is used to identify ammonia gas (which is pungent)?

Answer 5

Moist red litmus paper near the mouth of the test tube, which turns blue

Question 6

What are the results of litmus paper test for sulfur dioxide gas?

Answer 6

Blue litmus paper turns red.
Colourless pungent gas, sulfur dioxide gas evolved.
Gas evolved turned purple acidified potassium manganate (VII) colourless.
Gas evolved turned orange acidified potassium dichromate (VI) green.

Question 7

What are the results of the litmus paper test for Chlorine gas?

Answer 7

Red litmus paper turns white.
Blue litmus paper turns red then white (bleaches).
Pale yellowish green and pungent gas evolved.