why does hydrogen have to be collected in an upturned test tube?

Answer 1

Hydrogen is lighter than air so it moves upwards, an upturned test tube traps in in a confined space by stoping it moving up

Answer 2

Lighter substances like hydrogen floats to the top.

An upturn text tube seems would be able to collect it at the top.

However it can as well be downturn as long as it is on top i.e in an Elevated position relatively where it's being extracted from.
But you must understand that even in the text tube the lighter hydrogen stills collect on top whilst the unwanted air at the lower end.
So making it upturn means the
1.air is pushed down
2.In the case of leak or detaching it from the rest of the apparatus the air at the lower end could escape rather than the wanted hydrogen on top

Try it

Answer 3

I am assuming you are talking about hydrolyzing water to break it down into Hydrogen and Oxygen. The hydrogen doesn't have to be collected in a test tube. Any air tight container such as a bottle or jar will do. Whatever you use to collect it must be turned upside down or the hydrogen will just bubble through the water and enter the atmosphere. Also, the collection vessel must be full of water with no air in it. If there is air in it, the hydrogen will just mix with the air. If the container is full of water, the hydrogen will displace the water and fill the vessel with pure hydrogen.

Answer 4

All gases produced in laboratory experiments are best collected in this way. The test tube starts off full of water and ends up full of the gas (plus some water vapour). If you just put the nozzle into an empty (i.e. air-filled) tube you'd never know how much gas and how much air was in the tube. Nearly all gases are colourless.

There are a few extremely water-soluble gases this method would not suit but, as a student, you probably wouldn't make them.

Answer 5

Hydogen must be collected in an upsidedown test tube because hydroge is less dense than air so it rises. It is like co2. Co2 is more dense than air so is sinks. If you spray a co2 fire extinguisher at a fire on the celing, nothing will happen because the co2 has sunk to the bottom of the room. Also hydrogen keeps blimps afloat. If you put co2 into a blimp, the blimp will not fly

Answer 6

Because it is a gas, aand also odorless and colorless, so any gas released cannot escape if caught like this, as the gas will always travel up the test tube and so remain in the end.
Hydrogen is also highly flammable, and so must be kept secure to avoid explosions- I know someone who burnt a workbench after Hydrogen escaped and hit the bunsen flame. For experiments this method is both safe and practical.

Answer 7

It is not lighter than air - it is less dense than air. It would just float off if it wasn't collected in an inverted test tube.

Answer 8

Strangely enough hydrogen is lighter than air

Answer 9

Because it's lighter than air and so you want to stop it escaping.

Unless, of course, this is a trick question and the answer is 'because if you don't collect it and it's anywhere near a spark it'll explode.'

Answer 10

because it is lighter than air and will float out into the surrounding area if you do not

Hydrogen has an mass of 1g per every 24 meters squared, air on the other hand has a mass of about 14.5g per every 24 meters

hope this helps