Why must the evaporating dish be cooled

If we can't tunnel through the Earth, how do we know what's at its center? Why must you allow the evaporating dish to cool before measuring its mass? A lady introduce her husband's name with saying by which can stop or move train what is that name. Give points yo advocate thst biology is linked with physics chemistry mathsmatics geography. All Rights Reserved. The material on this site can not be reproduced, distributed, transmitted, cached or otherwise used, except with prior written permission of Multiply.

Hottest Questions. Previously Viewed. Unanswered Questions. Wiki User The temperature of the dish changes the mass, so you must let it cool to get the precise measurement. Another reason that you must wait for the dish to cool could be for safety precautions, or just to prevent damage to the scale. Related Multivariate calculus in python Asked in Chemistry Why must the evaporating dish cool before measuring the mass of a substance?

An evaporating dish must cool before measuring the mass of a substance. This is so that the energized particles settle and the mass can be measured accurately. Asked in Chemistry Why must an evaporating dish cool before measuring its mass? I think this is the answer I'm just guessing: hahahaha. Asked in Chemistry, Evaporation and Condensation Why must you allow evaporating dishes to cool before measuring the mass?

More Vapours come out of evaporating dishes when hot, and there is loss of some weight during this process. So the mass is measured after cooling. Asked in Chemistry, Evaporation and Condensation Why is it important to allow your evaporating dish and its contents to cool to room temperature before weighing them? A balance work well at a constant temperature of 20 0C. Asked in Turkeys How long to cool turkey before carving? Once the bird has completed cooking allow 20 minutes uncocered to allow breast to cool.

This will allow you to carve without the meat shredding to bits. The cooler it is aalowed to get the smoother the carving process will go. You don't have to let it cool down before carving, but if you want, let it cool down for about 30 mins to where you can handle it.

Then transfer to a plate and carve it. Asked in Chemistry, Evaporation and Condensation Why does water evaporating from our skin cool us down? Evaporation is an endothermic process. Yes it can. The highest velocity molecules are lost.Hot Threads. Featured Threads.

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Log in Register. Search titles only. Search Advanced search…. Log in. Forums Physics Other Physics Topics. JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding. Does temperature affect mass? We were told in chemistry class to weigh an evaporating dish after it cooled. Does it's temperature affect it's mass? Gokul Staff Emeritus. Science Advisor. Gold Member. In general, the temperature does not affect the mass of a closed system.

In your class, you are probably allowing something to cool, so that there is no more evaporation happening. That, or they don't want you to burn your fingers touching a hot object. What's in the dish, anyway? We were evaporating the water out of this hydrate to get an anhydrous compound. The goal was to find the ratio of water molecules to copper sulfate molecules. One of the questioins she asked us was why we should take the mass of the evaporating dish after it cools. I can only think this is a safety measure.

Also, depending on what kind of balance you are using, weighing something that's hot may give a faulty reading or might even damage the balance.

Do you use a metal balace which uses moments or a digical balance which uses springs? And I'll repeat :Temperature does not affect mass directly. In your particular example, it would be more accurate if you weigh the dish while still little hot. When the copper sulfate cools, being slightly hygroscopic, it will start to re-absorb moisture from the atmosphere.

If you wait too long for it to cool, it may have re-absorbed a considerable amount of moisture that your calculation will yield an underestimate. Insights Author.As part of the procedure for the determination of the sulfate content of an unknown sample it will be necessary to accurately determine the empty weights of a set of crucibles. This is accomplished by first cleaning the crucible and then heating them in the flame of a Tirrel burner.

They are then cooled and weighed. This process of heating and cooling is repeated until successive weighings agree to within 0. The procedure will, in addition, acquaint the student with the use of the analytical balance and the proper use of the desiccator. Be sure that you read the appendix section dealing with the use of desiccator.

why must the evaporating dish be cooled

Wash and rinse four 10 ml crucibles and their lids. Identify each of the crucibles by means of existing visual differences. Carefully note in your lab notebook what these identifying marks are and assign a number to each crucible. Do not use marking pens or pencils to mark your crucibles. The high heat which will be used to take them to constant weight will obliterate such markings and more importantly will affect their weight in an unpredictable manner.

why must the evaporating dish be cooled

The lids to the crucibles do not need to be taken to constant weight, however, they should be clean. Place a Tirrel burner under the crucible and adjust the flame of the burner to give a non-luminous flame with a full gas supply. The tip of the flame cone should be just below but not touching the crucible. Heat the crucible at red heat in this manner for minutes. Allow it to cool for a few minutes and then place it in the desiccator. Reheat and reweigh it until successive weighings agree to within 0.

Your first exercise teaches you some skills on the proper use of the laboratory burner in this case called a Tirill Burnerthe 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.

why must the evaporating dish be cooled

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.

Evaporating dish

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 leftbut 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.Changes in air currents caused by the heated dish can effect the scales.

An analytical balance measuring mass to the nearest 0. The mass of the empty evaporating dish or the tared dish with the original Copper II sulfate pentahydrate was performed with the dish at ambient room temperature.

After the dish is heat for a sufficiently long time to drive off the hydrated water, the dish must be allowed to cool to room temperature before the final mass reading. If you are allowed to do this, heat an empty evaporating dish and then place it on a balance and watch the mass fluctuate. This might even impress your teacher. Because if it is not cool there may be more evaporation of liquid going on that will change the mass that is left on the dish. Answer Save.

Richard Lv 7. Favorite Answer. Rich Z Lv 7.

why must the evaporating dish be cooled

Pseudo Obscure Lv 6. Probably because a hot item makes the air around it move, throwing off the scale. How do you think about the answers? You can sign in to vote the answer. Still have questions? Get your answers by asking now.An evaporating dish is a piece of laboratory glassware used for the evaporation of solutions and supernatant liquids, [note 1] and sometimes to their melting point.

Evaporating dishes are used to evaporate excess solvents — most commonly water — to produce a concentrated solution or a solid precipitate of the dissolved substance. Most are made of porcelain or borosilicate glass. Shallow glass evaporating dishes are commonly termed "watch glasses", since they resemble the front window of a pocket watch.

The evaporator is used most often in quantitative analysis. In the determination of silicon content in an organic sample, a small and accurately-measured quantity of a substance is added to the large amount of sulfuric acidthen heated in an evaporating dish. The dish is heated with a Bunsen burneruntil only stable precipitate remains, which contains the silica content. The dish is then closed and heated at high temperature until completely clean, fused silica is produced.

Comparison of the initial weight of the substance and that of the fused silica allows the content of silicon in the sample to be determined. When heating liquid in an evaporating dish, the low walls encourage splashes and so stirring or swirling of evaporating liquids is considered bad practice, owing to the risk of spillage.

Evaporation, especially in production quantities rather than merely for analysis, is now mostly performed in a rotary evaporator. This is preferred because it works much faster and may be used under vacuum, avoiding unwanted reactions with the atmosphere and allowing control of noxious fumes. Evaporation under vacuum also reduces the severity of bumping and violent ebullition. From Wikipedia, the free encyclopedia.

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why must you allow the evaporating dish to cool before measuring its mass?

Laboratory equipment. Stands Clamps Holders. Dean—Stark Soxhlet extractor Kipp's. Boston round Pycnometer.If we can't tunnel through the Earth, how do we know what's at its center? Why must the evaporating dish cool before measuring the mass of a substance? A lady introduce her husband's name with saying by which can stop or move train what is that name.

Give points yo advocate thst biology is linked with physics chemistry mathsmatics geography. All Rights Reserved. The material on this site can not be reproduced, distributed, transmitted, cached or otherwise used, except with prior written permission of Multiply. Hottest Questions. Previously Viewed. Unanswered Questions. Wiki User An evaporating dish must cool before measuring the mass of a substance.

This is so that the energized particles settle and the mass can be measured accurately. Related Questions Asked in Chemistry Why must an evaporating dish cool before measuring its mass? I think this is the answer I'm just guessing: hahahaha. Asked in Chemistry, Evaporation and Condensation Why must you allow evaporating dishes to cool before measuring the mass?

More Vapours come out of evaporating dishes when hot, and there is loss of some weight during this process.

why must an evaporating dish be cooled before finding its mass?

So the mass is measured after cooling. Asked in Science Why must you allow the evaporating dish to cool before measuring its mass? The temperature of the dish changes the mass, so you must let it cool to get the precise measurement. Another reason that you must wait for the dish to cool could be for safety precautions, or just to prevent damage to the scale.

Asked in Chemistry, Evaporation and Condensation Why is it important to allow your evaporating dish and its contents to cool to room temperature before weighing them? A balance work well at a constant temperature of 20 0C.

Asked in Chemistry, Evaporation and Condensation Why does water evaporating from our skin cool us down? Evaporation is an endothermic process. The thermometer works by measuring the temperature of the air or liquid around it. The substance being tested will heat or cool down the liquid in the thermometer to the temperature that it is. The highest velocity molecules are lost. Asked in Meteorology and Weather When a substance evaporates does it cool down or warm up?

It has to warm and then cool. Asked in Relationships, Cardiovascular Health How does your body cool down? The body cools itself down with the process of thermoregulation. Evaporating swear is able to cool down a person's body temperature through this process.Why must you allow the evaporating dish to cool before measuring its mass? All Rights Reserved. The material on this site can not be reproduced, distributed, transmitted, cached or otherwise used, except with prior written permission of Multiply.

Hottest Questions. Previously Viewed. Unanswered Questions. Wiki User February 18, PM. The temperature of the dish changes the mass, so you must let it cool to get the precise measurement. Another reason that you must wait for the dish to cool could be for safety precautions, or just to prevent damage to the scale. Related Questions Asked in Chemistry Why must the evaporating dish cool before measuring the mass of a substance?

An evaporating dish must cool before measuring the mass of a substance. This is so that the energized particles settle and the mass can be measured accurately. Asked in Chemistry Why must an evaporating dish cool before measuring its mass? I think this is the answer I'm just guessing: hahahaha. Asked in Chemistry, Evaporation and Condensation Why must you allow evaporating dishes to cool before measuring the mass?

More Vapours come out of evaporating dishes when hot, and there is loss of some weight during this process. So the mass is measured after cooling. Asked in Chemistry, Evaporation and Condensation Why is it important to allow your evaporating dish and its contents to cool to room temperature before weighing them? A balance work well at a constant temperature of 20 0C. Asked in Turkeys How long to cool turkey before carving? Once the bird has completed cooking allow 20 minutes uncocered to allow breast to cool.

This will allow you to carve without the meat shredding to bits. The cooler it is aalowed to get the smoother the carving process will go. You don't have to let it cool down before carving, but if you want, let it cool down for about 30 mins to where you can handle it. Then transfer to a plate and carve it.

Asked in Chemistry, Evaporation and Condensation Why does water evaporating from our skin cool us down? Evaporation is an endothermic process. Yes it can. The highest velocity molecules are lost. Asked in Relationships, Cardiovascular Health How does your body cool down? The body cools itself down with the process of thermoregulation. Evaporating swear is able to cool down a person's body temperature through this process.

Asked in Units of Measure What is the largest measuring units of grams? Asked in Global Warming, Planetary Science, Planet Mercury Does the atmosphere allow heat to escape quickly in order to cool the planet?

No the atmosphere does not allow heat to escape quickly to cool the planet. Asked in Science, Sanitization and Germs Why does your hand feel cool when you put hand sanitizer on the back of it. What is happening to the alcohol in the hand sanitizer?

The alcohol is evaporating, sucking some warmth from your hand as it does, making it feel cool.


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