How To Collect A Gas Using Water Displacement

Collecting a gas via water displacement is a common laboratory technique used in chemistry to isolate and capture gases that are less dense than water. This method is especially useful for gases that are not highly soluble in water. Here's how you can collect a gas using water displacement:
Materials and Equipment:
Gas source (e.g., a chemical reaction that produces the gas).
Gas collection apparatus, which typically includes:
Gas generator (e.g., a flask or test tube where the gas is produced).
Delivery tube (a tube connecting the gas generator to the collection vessel).
Collection vessel (e.g., an inverted graduated cylinder or gas syringe).
Water trough or container.
Water.
Clamp stand and clamps (for holding the apparatus in place).
Rubber stoppers or corks (to seal the openings).
Procedure:
Set up a clamp stand and attach a clamp to it to hold the gas generator in place. Ensure the gas generator is secure.
Place the gas collection vessel (e.g., a graduated cylinder) in the water trough. Fill the trough with water so that it covers the graduated cylinder. The graduated cylinder should be completely filled with water.
Fill the gas generator (e.g., a flask or test tube) with the substance that will produce the gas. Make sure the gas generator is securely fitted with a stopper or cork, except for the delivery tube.
Connect one end of the delivery tube to the opening in the stopper or cork of the gas generator. Make sure the connection is airtight.
Position the other end of the delivery tube below the water level in the graduated cylinder inside the water trough. Ensure that the delivery tube does not touch the bottom of the graduated cylinder and that it is completely submerged in the water.
Begin the reaction or process that generates the gas in the gas generator. As the gas is produced, it will displace water in the graduated cylinder and rise to the top.
Allow the gas to collect until the gas generator is no longer producing gas or until you have collected the desired amount of gas.
Carefully remove the delivery tube from the water and stop the gas-producing reaction if necessary.
To measure the volume of gas collected, read the volume of displaced water in the graduated cylinder. This volume represents the volume of the gas collected. Be sure to account for the water vapor pressure and correct for temperature and pressure if needed.
Once you have collected the gas and made any necessary measurements or calculations, remove the gas collection vessel from the water trough.
Carefully release the gas from the vessel for further analysis or use by removing the stopper or cork and allowing the gas to escape.
Collecting a gas via water displacement allows for the safe and quantitative collection of gases produced in chemical reactions. This method is particularly useful for gases that may react with or dissolve in water and for experiments where the volume of the gas collected is important.
00:00 Introduction
01:23 Water
02:35 Questions