Theory behind gas tubes in lab experiments

In summary, gas tubes are used for transporting gases in chemical experiments. The length of the tubes can vary, with entering tubes typically being longer than exiting tubes. This is because the entering tube needs to reach into a liquid, while the exiting tube should only allow gas to pass through. Sometimes, the entering tube is submerged in the liquid while other times it is not. There are instances where the exiting tube may also be submerged in a liquid, such as when removing CO2 using a solution of sodium hydroxide. It is not possible to only suck out insoluble gases by plugging the delivery tube in water, as both dissolved gases and the liquid will be sucked out. Overall, gas tubes operate based on a pressure difference and are used
  • #1
Faiq
348
16
For chemical experiments that involve gases as reactant and products, gas tube are used for their transport.

Q1. Why are there differences in length of gas tube when in a round flask. In most case, entering tubes are longer than exiting tubes? Why is that?

Q2. Why is sometimes the entering tubes submerged in the liquid (that is present in the flask) whereas sometimes they aren't?

Q3. Are there any scenarios for which exiting tubes are submerged in the water/solvent?
 
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  • #2
If you want the gas entering to go through a liquid, it needs the be longer to plunge in the liquid. On exit, you want only gas, so that tube has to be shorter, otherwise you will get liquid out.

There are different reasons why you would want a gas to first go through a liquid. For instance, a solution of sodium hydroxide can be used to remove CO2. I guess that in some cases the liquid is used to keep the gases from going back through the entry tube.
 
  • #3
Okay perfect thank you.

Is it also possible to just suck out insoluble gases by plugining the delivery tube in water?
 
  • #4
If you drink coke through a straw, do you suck out dissolved CO2, or the coke?
 
  • #5
Both I think
 
  • #6
Can you suck just the gas?
 
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Likes jim mcnamara
  • #7
No I don't think so.

Thank you very much.
 
  • #8
So basically these gas tubes are nothing but suction tubes that suck due to a pressure difference.
 
  • #9
Yes, the pressure difference is the driving force (note: it doesn't have to be suction, all that matters is that there is a pressure difference), there is nothing else happening.
 

1. What is the theory behind gas tubes in lab experiments?

The theory behind gas tubes in lab experiments is based on the principles of gas laws, specifically Boyle's Law, Charles' Law, and the Ideal Gas Law. These laws describe the relationship between pressure, volume, temperature, and moles of gas in a closed system. Gas tubes in lab experiments are used to control and measure these variables in order to study the behavior of gases under different conditions.

2. How do gas tubes work in lab experiments?

Gas tubes typically consist of a glass or plastic tube with one end connected to a gas source and the other end open to the surrounding air. The gas source can be a cylinder, a balloon, or a chemical reaction. By adjusting the pressure, volume, and temperature of the gas in the tube, scientists can manipulate the behavior of the gas and observe its effects on other substances in the lab.

3. What are the different types of gas tubes used in lab experiments?

There are several types of gas tubes used in lab experiments, including U-shaped tubes, capillary tubes, and manometers. U-shaped tubes are used to demonstrate the principle of displacement and can also be used to measure gas pressure. Capillary tubes are used to accurately measure small volumes of gas. Manometers, which consist of a U-shaped tube containing a liquid, are used to measure differences in gas pressure between two points.

4. What precautions should be taken when working with gas tubes in lab experiments?

When working with gas tubes in lab experiments, it is important to handle them with care and avoid any sudden movements that could cause the gas to escape or the tube to break. It is also important to properly secure the gas source and ensure that all connections are tight to prevent any leaks. Additionally, proper ventilation should be maintained in the lab to prevent the build-up of potentially hazardous gases.

5. What are some common uses of gas tubes in lab experiments?

Gas tubes are used in a variety of lab experiments, including demonstrations of gas laws, investigations into gas behavior under different conditions, and the measurement of gas pressure and volume. They are also commonly used in experiments involving chemical reactions, such as the production of gases as a byproduct. Gas tubes are essential tools in the study of gases and their properties.

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