Question

Apparatus X: Downward delivery
Apparatus Y: Upward delivery
Gas A: More dense than Air

State why apparatus Y is less suitable than apparatus X to collect gas A.​

Answer 1

Answer:

Gases may sometimes be produced during chemical reactions. By collecting and measuring the volumes of gas produced, we can know more about the reaction which had taken place and may also use it as a reactant for another reaction.

The method used to collect a particular gas is dependent on its:

Solubility – its ability to dissolve in water and

Density – how “heavy” it is as compared to air.

Three common methods to collect a sample of gas are shown below:

Displacement of Water

Upwards Delivery

Downwards Delivery

Displacement of Water

Gas collection-Displacement of water (full pic)

This method is suitable for collecting gases which are insoluble or only slightly soluble in water.

As the gases cannot dissolve in water and are lighter in density than water, they would rise to the top of the gas jar and be collected there. Some examples of gases collected via this way include  

H

2

,  

O

2

and  

CO

2

.

Upwards Delivery

Gas collection-upwards delivery1

This method is used to collect gases which are soluble in water and has a lighter density as compared to air. Some examples of gases collected this way include  

. Here is a picture of the set-up: