Collection Over Water:
This method is suitable when the gas is sparingly soluble in water.
A delivery tube from the reaction flask is submerged into a container partially filled with water.
As the gas is generated from the reaction, it passes through the water and bubbles to the surface.
Any residual impurities or unreacted gases remain dissolved in the water, purifying the collected gas.
The gas can be displaced from the collection container by gently introducing a gas delivery tube connected to the collection flask. This pushes the collected gas into a separate container or for further use in experiments.
Upward Displacement of Air:
This method is appropriate for gases like ammonia, which are less dense than air.
The reaction flask is fitted with a delivery tube that extends upward into an inverted collection tube or gas jar placed upside down on a flat surface.
As ammonia gas is generated, its low density causes it to move upwards within the inverted collection tube.
The lighter ammonia gas displaces the heavier air initially present in the collection tube.
The ammonia gas gradually fills the collection tube, pushing the remaining air out through a small opening at the base or a stopcock if available.
Once the collection tube is filled with ammonia and no more air remains inside, it can be capped or sealed for storage or further analysis.
It's important to ensure the collection vessels or tubes used are dry before collecting ammonia gas to prevent any reactions or dilution of the gas by water vapor. Additionally, proper safety precautions should be taken while handling ammonia gas, as it can be harmful when inhaled in large concentrations.
