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Halogen Gas

February 13th, 2010 admin No comments

Halogen Gas

Collection of gas by the displacement of water is only possible if the gas is?

a) water insoluble.
b) heavier than air.
c) lighter than air.
d) water soluble.
e) a halogen or a noble gas.

I put C. but it's marked wrong.
What's the correct answer?

The correct answer is definitely "A"

displacement of water means you start with an inverted container filled with WATER. The gas is collected in the container and the pressure of the gas pushes the water out of the container.

It doesn't matter if the gas is heavier or lighter than air. As long as it's less dense than water it will rise to the top of the container and displace the water. So the answer isn't (B) or (C).. in fact, air isn't even part of this experiment.

If the gas dissolves in the water, then it won't collect in the container and it won't generate pressure to force the water out of the container.. So the answer is not (D)

and halogen vs noble gas doesn't matter either. it's still a gas. So it isn't (E) either.

so the correct answer is "A".. as long as the gas is insoluble in water, it can be collected via water displacement.