ساااااااعدوني بليييييييييز ماهو حجر الغليان...

صيدلانية سعودية

مشرفة قسم الصيدلة
ا​
لسلام عليكم


اخ​
باركم


مم​
كن طلب ولا تردوني


ممك​
ن احد يعرف لي حجر الغليان ؟؟



اه​
و يوضع في جهاز التقطير البسيط


وظ​
يفته ساعد تنظيم عملية الغليان حيث يوزع الحرارة على السائل كلخ ويتمص حدة الفوارق وبالتالي يمنع الانفجار .


تح​
يااااااااااتي ابي الاجااااااااااااااااااااااابه ضروووووووري



جز​
اكم الله الف خييييييييييراا

 
from wikipedia
Boiling chips or boiling stones or bumping granules, are small, irregularly shaped stones added to liquids to make them boil more smoothly. They provide nucleation sites so the liquid boils easily without becoming superheated. Without boiling chips, a liquid heated in a smooth container can become superheated and release vapor suddenly, sometimes violently. This sudden bubble of gas can cause the solution and reagents to be thrown out of the container, possibly causing severe burns, ruining an experiment, or simply making a mess.
Boiling chips are typically made of a porous material, such as alumina, calcium carbonate or carbon, and often have a nonreactive coating of PTFE (Teflon). This ensures that the boiling chips will provide effective nucleation sites, yet are chemically inert. In school laboratories, pieces of broken ceramic crucibles are often used.
Boiling chips should not be added to liquid that is already near its boiling point, as it could cause a large amount of vapor to form all at once. This could cause hot liquid to be expelled from the container, possibly causing heat or chemical burns

from other sources

Boiling chips are small, insoluble, porous stones made of calcium carbonate or silicon carbide. These stones have pores inside which provide cavities both to trap air and to provide spaces where bubbles of solvent vapor can form. When a boiling chip is heated in a solvent, it releases tiny bubbles. These bubbles ensure even boiling and prevent bumping and boiling over and loss of the solution.
Always use a boiling chip when heating a solvent.
Never add a boiling chip to a hot solvent, because it can cause immediate boiling over of the solution. If you forget to add a boiling chip before you begin, you must cool the solution before adding one to prevent product loss. Boiling chips cannot be re-used since the pores inside these stones become filled with liquid on cooling.





These tiny boiling chips are very porous rocks which release bubbles of entrapped air to the solution being heated. These bubbles provide a path by which the vapour of the boiling liquid can be smoothly led to the surface and released. It should be noted here that a boiling chip may not be used twice; it must never be added to a hot solution (near its boiling point) since violent frothing will occur.




Boiling Chips, what are they and why do we use them?
Liquids often boil in an uneven fashion, or "bump" as it's called in chemistry. Bumping occurs frequently when there aren't any scratches on the walls of the container to help bubbles form. Superheating then occurs- because the walls of your boiling pot are smooth and bubbles of gas cannot easily form, the temperature of the liquid can actually rise above it's boiling point without boiling!. This can be dangerous because when bubbles finally do form, they usually erupt violently because so much of the liquid is just itching to boil but hasn't been able to, that it all goes at once!

Bumping is easily prevented by adding a few boiling chips to the liquid, which provide a rough surface upon which bubbles can form. When boiling chips are used, essentially all of the bubbles that rise through the solution will form on the surface of these chips.
Boiling chips are small, insoluble, stones made of calcium carbonate, silicon carbide, or carbon (crushed coal) just to name a few. These stones have pores inside or sharp points outside which provide a place for bubbles to easily form.
 
بسم الله الرحمن الرحيم

السلام عليكم ورحمة الله وبركاته

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دى أحجار الغليان أو
Boiling Stones, Glass Beads and Tamer Tabs™

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Teflon® boiling stones (WLS-8210) promote gentle, efficient boiling and minimize bumping during reflux. Easily cleaned, noncontaminating, chemically inert and will not scratch glassware. May be used to 260°C. In 450 g bottle.

Solid soda lime glass beads (WLS-39835-D) are nearly spherical without perforation. Promote boiling and eliminate reflux to 260°C. Chemically inert. Average dia: 6 mm. Package of 1 lb.

Use Tamer Tabs boiling chips (WLC3295S) when a slow boil is needed over an extended time period. Minimizes bumping during reflux. May be used to 260°C. Chemically inert. 250 g.
http://www.sargentwelch.com/product...+Stones,+Glass+Beads+and+Tamer+Tabs™_E_

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http://www.engineering.ucsb.edu/articles/life_saving_sand
Zeolites – the term comes from the Greek words for "boil" and "stone" – are minerals that occur naturally in volcanic formations and have been synthesized in many forms. Highly porous, the rocks can hold huge amounts of water, which causes zeolite rocks to jump around as the water evaporates under rapid heating – hence the "boiling" label. Zeolites are also energetic when they absorb water, easily heating up to water's boiling point. They have a structure and chemistry that make them highly useful in water purification, oil refining, and other processes that involve the filtering and separation of liquid or gas compounds. Every gallon of gasoline has been processed through zeolites, Stucky notes, and zeolites are used in laundry detergent to soften the wash water by replacing calcium with sodium.
Zeolites have played a role in military first aid since 2002, when the Navy and Marine Corps adopted QuikClot to staunch battlefield wounds (the Army also uses a different coagulant, called HemCon, made from the chitin molecules in shrimp shells). As Stucky and others tell the story, the idea of a zeolite blood-clotting agent came about by accident when inventor Frank Hursey, who was working with absorptive materials, cut himself shaving and stopped the bleeding with a handy zeolite sample. Hursey went on to develop QuikClot and founded Z-Medica Corp., the Connecticut-based company that markets the product. Today all U.S. military branches carry packets of the granulated material, a synthetic zeolite that can quickly be applied to hemorrhaging wounds to kick-start the clotting process.

Just how many lives have been saved by this one product? It's impossible to say for sure, given all the factors that determine the survival rate after battlefield injuries. But along with other advances in first aid and trauma care, QuikClot has contributed to an encouraging trend in military medicine. According to a 2006 study co-authored by Col. John Holcomb, a trauma surgeon who heads the Army’s Institute of Surgical Research, the "case fatality" rate in Afghanistan and Iraq since 2001 was 9.4. In other words, slightly more than nine out of 100 troops injured but not immediately killed in battle die eventually from their wounds or from complications. In the context of military history, that number reflects a remarkable advance. The case fatality rate was 15.8 in the Vietnam War and 19.1 in World War II. Much earlier, in the U.S. Civil War, Stucky says an injured soldier had a 15% to 20% chance of survival. That amounts to a case fatality rate of at least 80.

On the home front, first responders such as police and paramedics also started to use QuikClot when it was adopted for military use. But the product still needed improvement. Early uses in the field turned up a serious side-effect. The QuikClot "sand" stopped bleeding but also released intense heat that sometimes caused second- or third-degree burns. Stucky got an urgent request from the Office of Naval Research (ONR) in mid-2003 to deal with the problem. The ONR gave him a short-term grant to study how to cool the QuikClot without robbing it of its effectiveness. It wanted results ASAP. This was not your typical research grant. "A monumental timescale compression of academic research to field application was required," Stucky says "and the three-way interfaces involving Z-Medica, the University, and ONR that made the science and the technology transfer for a medical product possible have been fantastic."

Stucky's side of the project got under way at UCSB in 2004. Although all the UCSB researchers’ funding came from ONR, they worked closely with people at Z-Medica who were also pursuing independent investigations. Stucky and Z-Medica realized that the burns could be prevented by optimizing the water content of the zeolite while keeping QuikClot's efficacy.

Most of the heat is released in the adsorption of the first small amounts of water, Stucky says, so that QuikClot could be kept much cooler if it were less dehydrated when applied to a wound. Stucky also researched other methods of decreasing the heat. The temperature of adsorption could be controlled by changing the ratios of calcium and sodium; the stronger bonds formed by calcium and water produce more heat than the somewhat weaker sodium bonds. Another method discovered by Stucky's research group is to add silver ions that can both cool the clotting process and take advantage of silver’s antibiotic property – an important bonus. The new QuikClot was tested in test-tube blood samples and on pigs. It worked, and this year it was released for the first time as an over-the-counter consumer product under the name QuikClot Sport™ Silver.

Beyond the improvement of QuikClot, Stucky sees important advances in knowledge from the work that he and Z-Medica have done. "I saw it as an opportunity to get in and understand a biosystem process; and, to create new materials that might provide a helpful interface with living systems," Stucky says. The blood coagulation cascade, as that process is technically called, is not fully understood. But the technology for controlling it is rapidly moving forward. "We can now predictively synthesize inorganic and composite agents that either induce coagulation or prevent coagulation," he says. More sophisticated products also may be on the way, such as toothpaste-like clotting agents from bio-active glass, with uniform pores able to deliver antibiotics or other drugs. In short, the chemistry of boiling stones seems destined to save more lives
 
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