In my tb it states that hcl is collected by upward displacement of air since it is 1.28 times heavier that air......but in the study material given here it states that HCL gas is collected by upward displacement of water since it is lighter that air. Plz explain and plz tell which one among them is right.

Dear Student,

Gases lighter than air are collected by upward displacement of air and gases heavier than air are collected by downward displacement of air.

Gases which are less denser (lighter) than air. e.g. Hydrogen tend to move upwards hence the source of supply has to be lower in elevation than the destination and its called upward delivery. The less dense gas rises upwards, and displaces, the more dense air downwards. Hence upward delivery is used.

A gas which is lighter than air, will be displaced upward by air. Thus, such gases can be collected by upward displacement by air. Some gases lighter than air are Methane (CH4), Hydrogen (H2), Carbon monoxide (CO), Ammonia (NH3) etc.

Hope this information will clear your doubts about the topic.

If you have any more doubts just ask here on the forum and our experts will try to help you out as soon as possible.



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