In the laboratory, hydrogen gas is collected by downward displacement of air. Which property of hydrogen makes this method suitable?
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Correct answer
A. Hydrogen is less dense than air
Principle or equation
Gases less dense than air can be collected by downward displacement of air (upward delivery) because they rise and displace the heavier air from the top of an inverted container.
Why this answer is correct
Hydrogen has a very low density (about 0.09 g/L) compared to air (about 1.29 g/L). It rises, so it is collected in an inverted bottle by downward displacement of air. Solubility and color are not relevant to this collection method.
Example
A gas with density lower than air, such as hydrogen or ammonia, can be collected by upward delivery (downward displacement of air).
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