Your first exercise teaches you some skills on the proper use of the laboratory burner in this case called a Tirill Burner , the adjustment of the flame and the proper placement of a crucible which is to be heated to constant weight. You ought to make sure at the outset that the crucibles you use have indelible identifying marks on them. Sometimes there are indentations left during the manufacture of a crucible which will allow you to distinguish one from another.
More likely, there will be a letter or number written into the side by a former student, such as the one shown at the left. Note the "A" scratched into the glossy surface. This can be done with the diamond pencil available in the lab, as shown at the right. The hottest part of the flame is at the top of the bright cone of oxidation. The zone beneath the sharp point of the cone is filled with a rising mixture of cool gases not yet in the process of combustion.
Although the rim around this zone is quite hot, the gases inside are essentially at room temperature. See that placement on the left. Such a placement is not recommended Note the correct placement of the crucible in the photograph at the right.
The crucible may be placed right side up, as in the left photo, or on its side, as in the right photo. Heating it on its side is preferred because the overall strain on the ceramic material at the high temperatures used is somewhat less. The crucible ought to be heated to incandescence for minutes left. At the end of this time, remove the flame and allow the crucible to cool on the iron triangle for a few minutes right. When transferring a crucible to the dessicator tongs must be used.
If the crucible has been allowed to cool, you may use bare tongs left , but if you must transfer a hot crucible, make sure that you cover the ends of the tongs with aluminum foil right as the paint on the tongs might melt onto the crucible and change its weight.
Make sure you grab the crucible on the edge as shown. Don't try to pick up a crucible by squeezing the tongs on the outer rim both because the crucible may slip from your grip owing to its slick walls. There is also the possibility of breaking a hot crucible that way. Place the cool crucible into one of the holes in the plate in your dessicator and cover until it has reached room temperature.
At that time you may remove it for weighing. This keeps the chemicals dry and makes them last longer. Based in Portland, Ore. Her articles have appeared in magazines such as "Herb Companion" and "Northwest Travel" and she is the author of six books. Gallons to Kilograms Conversion. How to Measure Conductivity in Water. How to Test for Ethanol Content.
What Is Anhydrous Methanol? How to Calculate the Density of a Solution. How to Make a Coffee-cup Calorimeter. How to Make Agar Plates. Best Answer. Study guides. Q: Why is a desiccator used to cool a crucible? Write your answer Related questions. Why must The Crucible by Arthur Miller be cooled in a desiccator? What is a desiccator most commonly used for?
Why is it best to use a desiccator for cooling of the crucible and lid after heating? Why is it best to use a desiccator for the cooling of the crucible and lid after heating? Why cool the crucible before weighing?
What is a crucible tong? What is crucible used for? Alliteration in the crucible? What is a desiccator? Why are crucible and tongs used to transfer The Crucible after heating and before weighing? Uses of porcelain crucible? What is crucible tung? What is a crucible cover used for in chemistry? How do you take care of desiccator?
What laboratory apparatus can keep grams of a compount from absorbing atmospheri moisture? What is the use of desiccator? What is a crucible and cover? What is the use of crucible? What are the uses of clay triangle? What is clay triangle how it is use? Crucible and cover uses? What is a porcelain crucible and lid?
Who long you can left the simple in the desiccator?
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