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An evaporating dish is a piece of laboratory-glasswareused for the evaporationof solids and supernatant fluidsevaporating-dish, 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 of porcelainor borosilicate-glass. Shallow glass evaporating dishes are commonly termed "watch glasses", from their original use as the front window of a pocket-watch-2.evaporating-dishSome used for high-temperature work are of refractory-metals, usually of platinum, owing to its non-reactive behaviour and low risk of contamination.

The capacity of evaporators is usually small - in the range 3-10 ml-abbreviation. Larger dishes, up to 100 ml, are different in shape, and are more hemispherical.

The evaporator is used most often in quantitative-analysis.

In the determination of siliconcontent in an organic sample, a small and accurately-measured quantity of a substance is added to the large amount of sulfuric-acid, then heated in an evaporating dish. The dish is heated with a bunsen-burner, until 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 to the content of silicon in the sample to be determined.

A generic evaporator

The shape of the evaporating dish encourages evaporation in two ways:

  • The shell is relatively flat. A relatively large liquid surface promotes evaporation.
  • If heated in a flask or beaker, a part of the evaporated liquid condenses on the vessel walls and flows back into the solution. This does not happen in a dish.

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 in a laboratory, 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-chemistryand violent ebullition.

-Jobelle Flores Pelagio

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Related Questions

Can an evaporating dish be heated on a hot plate?

Yes, an evaporating dish can be heated on a hot plate to facilitate the evaporation of a solution. However, it is important to control the temperature to avoid overheating or damaging the dish. use a heat-resistant container if heating directly on the hot plate.


HOW TO USE THE EVAPORATING DISH?

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What connects to a evaporating dish?

An evaporating dish is typically connected to a heating source like a Bunsen burner or a hot plate in a laboratory setting. This connection allows for the controlled evaporation of a liquid from the dish, leaving behind any solid residue.


Do you use in the plate or on the plate?

You would use "on the plate" when referring to placing something on top of a plate. For example, "The steak is on the plate." If referring to containing something inside a plate, you could use "in the plate," but it's less common.


Why evaporating dish is not heated directly over Bunsen burner?

Evaporating dishes are usually made of glass or porcelain which can crack or shatter when heated unevenly. Directly heating the dish over a Bunsen burner can cause temperature gradients within the dish leading to uneven heating and potential breakage. It is safer to use a hot plate or a water bath for more uniform heating.


What is the scientific name of laboratory glass plate?

The little white one? It's called an evaporating dish that you put your items and water in and let it evaporate over the Bunsen burner.


what is deposited when an evaporating dish is put on top of a luminous flame?

luminous flame gives partial combustion so you can see some black unburnt vapours deposited on the plate


Why do you use an evaporating basin to get salt from seawater instead of a beaker?

to increase the surface area of evaporation


How do you use evaporating-dish?

The name is clear: it is used to evaporate a liquid to obtain the solid residue.


Is direct heating advisable when evaporating NaCl solution?

no, it is more safe to use water bath :)


What different between car's yellow number plate n white number plate if i buy use car?

A yellow no plate of a car is indicate that the car is use as a taxi but a white no plate is stand that it is use for personal use.


How evaporation causes cooling 6 examples?

In a given liquid, the atoms or molecules which are moving the fastest, and hence have the highest temperature, are the ones that are most likely to leave the liquid and evaporate. The atoms or molecules that they leave behind will therefore be cooler. Examples: evaporating water evaporating alcohol evaporating liquid nitrogen evaporating glycerol evaporating liquid helium evaporating acetone.