After the solid has dissolved, it is better to wait until the solution has reached room temperature before placing the system in an ice bath.判断题

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How much hot solvent should be used to dissolve the solids?

Recrystallisation is a very important technique in synthetic chemistry. A critical step is in selecting a solvent system where the impurities are very soluble but the product is only partly soluble. The mixture for purification is heated to dissolve all of the product in a super saturated solution. On cooling the product starts to crystallise out of solution as it's solubility is poor at room temperature. If you have chosen your solvent correctly your impurity will stay in solution. Watch this short video and answer the following questions about recrystallisation. Note: this is an example recrystallisation and not actually a benzocaine recrystallisation. Recrystallisation video Why do we allow our recrystallisation to cool slowly? Please select the most accurate answer.

Recrystallisation is a very important technique in synthetic chemistry. A critical step is in selecting a solvent system where the impurities are very soluble but the product is only partly soluble. The mixture for purification is heated to dissolve all of the product in a super saturated solution. On cooling the product starts to crystallise out of solution as it's solubility is poor at room temperature. If you have chosen your solvent correctly your impurity will stay in solution. Watch this short video and answer the following questions about recrystallisation. Note: this is an example recrystallisation and not actually a benzocaine recrystallisation. Video Player is loading.Play VideoPlaySkip BackwardSkip ForwardMuteCurrent Time 0:00/Duration 0:00Loaded: 0%Stream Type LIVESeek to live, currently behind liveLIVERemaining Time -0:00 1xPlayback Rate2x 1.75x 1.5x 1.25x 1x, selected 0.75x 0.5x ChaptersChapters Descriptionsdescriptions off, selected Captionscaptions and subtitles off, selected Audio TrackPicture-in-PictureFullscreenThis is a modal window.Beginning of dialog window. Escape will cancel and close the window.TextColor[select: White, Black, Red, Green, Blue, Yellow, Magenta, Cyan]Opacity[select: Opaque, Semi-Transparent]Text BackgroundColor[select: Black, White, Red, Green, Blue, Yellow, Magenta, Cyan]Opacity[select: Opaque, Semi-Transparent, Transparent]Caption Area BackgroundColor[select: Black, White, Red, Green, Blue, Yellow, Magenta, Cyan]Opacity[select: Transparent, Semi-Transparent, Opaque]Font Size[select: 50%, 75%, 100%, 125%, 150%, 175%, 200%, 300%, 400%]Text Edge Style[select: None, Raised, Depressed, Uniform, Drop shadow]Font Family[select: Proportional Sans-Serif, Monospace Sans-Serif, Proportional Serif, Monospace Serif, Casual, Script, Small Caps]ResetDoneClose Modal DialogEnd of dialog window. Why do we allow our recrystallisation to cool slowly? Please select the most accurate answer.

Question textFrance Info: La météo avec . . .Écoutez au bulletin de météo et répondez aux questions. https://elearning.swissedu.net/pluginfile.php/729515/question/questiontext/255175/11/974475/Radio%20France%20Info%20La%20me%CC%81te%CC%81o.m4aVideo Player is loading.Play VideoPlayMuteCurrent Time 0:00/Duration 1:07Loaded: 0.00%0:00Stream Type LIVESeek to live, currently behind liveLIVERemaining Time -1:07 1xPlayback Rate2x 1.75x 1.5x 1.25x 1x, selected 0.75x 0.5x ChaptersChapters Descriptionsdescriptions off, selected Captionscaptions settings, opens captions settings dialog captions off, selected Audio TrackPicture-in-PictureThis is a modal window.Beginning of dialog window. Escape will cancel and close the window.TextColor[select: White, Black, Red, Green, Blue, Yellow, Magenta, Cyan]Transparency[select: Opaque, Semi-Transparent]BackgroundColor[select: Black, White, Red, Green, Blue, Yellow, Magenta, Cyan]Transparency[select: Opaque, Semi-Transparent, Transparent]WindowColor[select: Black, White, Red, Green, Blue, Yellow, Magenta, Cyan]Transparency[select: Transparent, Semi-Transparent, Opaque]Font Size[select: 50%, 75%, 100%, 125%, 150%, 175%, 200%, 300%, 400%]Text Edge Style[select: None, Raised, Depressed, Uniform, Dropshadow]Font Family[select: Proportional Sans-Serif, Monospace Sans-Serif, Proportional Serif, Monospace Serif, Casual, Script, Small Caps]Reset restore all settings to the default valuesDoneClose Modal DialogEnd of dialog window. Pour commencer, un petit point sur la météo avec . . . .Questions:1 À quelle heure est le bulletin de météo? Il est à Answer 1 Question 11[input] heures2 Comment s'appelle la présentatrice? Elle s'appelle Answer 2 Question 11[select: , Mélodie Martine, Mélanie Martinet, Élodie Martin]3 On est en quelle saison? On est Answer 3 Question 11[select: , en printemps, en été, au printemps]La météo d'aujourd'hui: VRAI ou FAUX?Answer 4 Question 11[select: , VRAI, FAUX] Il fait un temps ensoleillé presque partout.Answer 5 Question 11[select: , VRAI, FAUX] Mais à Lyon et Clermont il grêle.Answer 6 Question 11[select: , VRAI, FAUX] Il y a peu de vent en Méditerranée.Answer 7 Question 11[select: , VRAI, FAUX] L'après-midi les températures vont monter.Et le weekend?Answer 8 Question 11[select: , VRAI, FAUX] Le weekend il fait beau partout en France. Comment sont les températures le matin? il fait Answer 9 Question 11[input] °C à Lille et Bordeauxil fait Answer 10 Question 11[input] °C à Brest il fait Answer 11 Question 11[input] °C à Bastia

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