Between The Second And Thrid Fingers
Wetting the glass tubing before inserting it into a stopper helps create a better seal by reducing the risk of air pockets. The water acts as a lubricant, making it easier to insert the glass tube into the stopper without damaging either component.
To find the density of a glass stopper, you need to measure its mass using a scale, then measure its volume by either water displacement method or calculating its dimensions if it has a regular shape. Divide the mass by the volume to calculate the density, usually in units of g/cm3 or kg/m3.
Yes, it is important to always put a glass stopper on top of the condenser during reflux to prevent evaporation of the solvent and loss of reactants or products. The stopper helps to maintain a closed system and ensure that the liquid is condensed and returned to the reaction flask.
In a chemical laboratory it is not so recommended to lubricate stoppers with a grease; this grease can be dissolved by reactants and the experiment become compromised. But some exceptions exist.
It is important to wear safety goggles and gloves when inserting glass tubing to protect against potential injury from broken glass. Covering the tubing and stopper with protective pads of cloth can help prevent the glass from shattering and causing harm if it breaks. These precautions reduce the risk of cuts and injuries to the hands and eyes.
It is best to grasp the sides of the stopper firmly with two hands and twist it gently back and forth to break the seal before pulling it out. Avoid pulling too hard as it may break the stopper.
If there is debris on the stopper it might be preventing a good seal. Try removing the rubber stopper and wipe it off to remove any debris that might be on it. Clean out the hole that the stopper goes into as well. This will help ensure a clean seal between the hole and the stopper. Put the stopper back into the hole, making sure it is a tight fit. If it still leaks you may need to buy a new stopper.
Grease the top of the bottle!
If strong bases are present in the glass-stopper bottles, they may react with the glass and etch it or change the concentration of the base. Hence plastic-stopper bottles are used for bases.
Wetting the glass tubing before inserting it into a stopper helps create a better seal by reducing the risk of air pockets. The water acts as a lubricant, making it easier to insert the glass tube into the stopper without damaging either component.
Run warm to hot water over the neck of the container. This will expand the neck and the stopper should come out.
See these two questions for the answer:[http://wiki.answers.com/Q/What_is_a_rubber_stopper_or_cork_stopper_and_how_are_they_usedWhat is a rubber stopper or cork stopper and how are they used?]and[http://wiki.answers.com/Q/What_is_a_glass_plate_and_how_is_it_usedWhat is a glass plate and how is it used?]
It can either be glass that has been ground to a powder, or two glass surfaces that have been ground to fit together precisely, such as a glass stopper in a glass chemical bottle.
Over time, the sodium hydroxide will react with the smidges of carbon dioxide in air to produce sodium carbonate, the white, crusty powder that you find around the rim of plastic capped stock bottles (for example). This powder will either prevent the ground glass stopper from sealing properly and exposing the contents to more air, or will in fact cement the ground glass stopper in the bottle, and make it impossible to remove.
never attempt to insert glass tubing that has a jagged end, all glass tubing should be fire polished before its inserted into a rubber stopper. Use water or glycerin as a lubricant at the end of the glass tubing before inserting it into the rubber stopper. ask teacher for proper lubricant. Protect hands and fingers by wearing leather gloves or placing a folded cloth between your hands and the tubing. hold it as close as possible to the part it is inserted to the rubber stopper. always point the tubing away from the palm of your hand that holds the stopper. use a twisting motion and push the tubing into the stopper. At the end of the experiment put on leather gloves or place the folded cloth between your hands and the tubing and remover the stoppers from the tubing to keep them from sticking to the glass. if it wont budge, use lubricant.
To find the density of a glass stopper, you need to measure its mass using a scale, then measure its volume by either water displacement method or calculating its dimensions if it has a regular shape. Divide the mass by the volume to calculate the density, usually in units of g/cm3 or kg/m3.
With a few exceptions (notably melting ice) objects expand when heated. If you run hot water on a bottle neck, the heat is applied directly to the bottle and only indirectly to the stopper inside the bottle, so the bottle heats first, and thereby expands sooner than the stopper does. An expanded bottle will exert less pressure on the stopper.