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For more information, please see full course syllabus of Organic Chemistry
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Lecture Comments (2)

1 answer

Last reply by: Professor Starkey
Tue Oct 10, 2017 1:30 AM

Post by Maryam Fayyazi on October 5, 2017

if we want to purify the crystals wouldnt it be easier to evaporate the solvent and keep the product as pure material instead of doing crystalization?

Introduction to Recrystallization

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Crystallization to Purify a Solid 0:10
    • Crude Solid
    • Hot Solution
    • Crystals
    • Supernatant Liquid
  • Theory of Crystallization 2:34
    • Theory of Crystallization
  • Analysis and Obtaining a Second Crop 3:40
    • Crystals → Melting Point, TLC
    • Supernatant Liquid → Crude Solid → Pure Solid
    • Crystallize Again → Pure Solid (2nd Crop)
  • Choosing a Solvent 5:19
    • 1. Product is Very Soluble at High Temperatures
    • 2. Product has Low Solubility at Low Temperatures
    • 3. Impurities are Soluble at All Temperatures
    • Check Handbooks for Suitable Solvents
  • Why Isn't This Dissolving?! 8:46
    • If Solid Remains When Solution is Hot
    • Still Not Dissolved in Hot Solvent?
  • Where Are My Crystals?! 12:23
    • If No Crystals Form When Solution is Cooled
    • Still No Crystals?
  • Tips, Tricks and Warnings 16:26
    • Always Use a Boiling Chip or Stick!
    • Use Charcoal to Remove Colored Impurities
    • Solvent Pairs May Be Used
    • Product May 'Oil Out'