cryst2 - Chem 267. Recrystallization - Part 2. (revised...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chem 267 . Recrystallization - Part 2 . (revised 7/10). Recrystallize benzoin if you did not do it the previous week. You will also recrystallize an unknown. Review the techniques such as vacuum (or suction) filtration and filtration using the pipet method. Lab Clean-up . For reasons of safety and effectiveness, an essential part of lab work is keeping the lab in a clean and orderly state. Please keep bottles capped. Many chemicals will lose their effectiveness or evaporate if left open to the atmosphere. If caps are not in place, the potential also exists for toxic chemicals to enter the lab atmosphere. Please clean up spills immediately so others do not become contaminated. Most of you will soon join a research group. You will quickly find that sloppy and unsafe behavior is not tolerated one bit by your advisor or coworkers. Learning good lab habits now will help greatly later on. Waste Disposal : place all liquid wastes from these experiments into the Nonhalogenated Liquid Waste container. In your prelab outlines remember to always include procedures for the proper disposal of wastes as described in the handout for that experiment. (1.) Purification of an Unknown . Using two different solvents you will recrystallize two 60 mg samples of an unknown that is contaminated with soluble impurities. Your TA will assign the unknown to you. You must first determine suitable recrystallization solvents by doing solubility tests and preparing a table as before. Several solvents are available to you in this experiment. These are water, methanol, ethanol, ligroin, and toluene. Try as many of these solvents as necessary to find at least two that work well. The ideal solvent is one that produces the highest recovery of the purest most well-formed crystals. One of the two that you choose will probably work better in terms of purification or yield. You will assess the effectiveness of a particular recrystallization by comparing
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 3

cryst2 - Chem 267. Recrystallization - Part 2. (revised...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online