ÐÏà¡±á>þÿ :<þÿÿÿ9ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿì¥Á%` ð¿âbjbj"x"x 4(@@âÿÿÿÿÿÿ¤èèèèèèèüDDDDXül2xxxxxxxxëíííííí$žh˜èxxxxxèèxx&```x^èxèxë`xë``?èè‹xl0«ÎÿÈDÖ.Wë<0l_,žRž‹‹8žèÃ(xx`xxxxxV xxxlxxxxüüüD@ üüü@ üüüèèèèèèÿÿÿÿThe Grasshopper's Guide to Cleaning Glassware A Chemistry Student approached the Master and asked, “Master, how do I achieve enlightenment in Chemistry?” The Master replied, “Wash your glassware.” Introduction Clean glassware is essential in chemistry. The problem is that the tolerance for shmutz varies with the work you are doing, and sometimes a chemist does not know how important clean glassware is to an experiment until it has failed. This document is designed to give an undergraduate chemistry student a brief introduction to what chemists mean by "clean" and how it can be achieved. There are two broad degrees of clean in chemistry; quantitative and normal. Quantitatively clean glassware is required for the most demanding applications where a quantity is being measured at high precision, such in analytical or physical chemistry. Glassware at this level of cleanliness has no residues (e. g., grease) or other impurities on it. Normal clean glassware is free of large amounts of impurities, but some grease may be tolerated. Glassware that has been cleaned normally is used where high degrees of precision are not required, such as in a synthesis. General Cleaning Tips The key to cleaning is doing it a timely manner; letting dirty glassware sit for long periods of time guarantees a harder cleaning job. Also take a minute to separate your glassware into a group which requires a higher degree of cleaning and one that does not. •Disassemble your apparatus as soon as possible after you are finished with it. Remove all stopcocks and stoppers from addition funnels, separatory funnels and the like. Ground glass stopcocks and stoppers will freeze in place if certain reactants (e. g., bases) were used in them. Triple rinse all surfaces with an appropriate solvent to remove traces of solvents and reaction mixtures, place these in the appropriate waste container. •Graduated cylinders, beakers, Erlenmeyer flasks, burets and pipettes that were only used to dispense or store reagents generally only need to be triple-rinsed with a compatible solvent followed by tap water and a final DI water rinse, if desired. Air dry on a drying rack. In some cases you may need to be more thorough, as described below. •Büchner funnels, etc. should be rinsed with an appropriate solvent to remove substances that are clinging to them. Follow this by tap water and DI water rinses and air dry. Health and Safety Considerations Even a task as simple as washing glassware at the sink is potentially hazardous. You must wear eye protection, appropriate for the task, at all times. Gloves are recommended, even for general cleaning, if the glassware contained an irritant, lachrymator or toxic material. Before cleaning be sure that any excess reagent has been disposed of properly and the vessel in which it was contained has been triple-rinsed into the waste container. General Cleaning Procedure The following steps should be followed for glassware for which a simple solvent rinse is not sufficient. If you need quantitatively clean glassware, these should be the first steps toward this goal, and more aggressive cleaning methods may be required (vide infra). •Degrease your glassware’s ground glass joints by wiping them with a paper towel soaked in a small amount of ether, acetone or other solvent (CAUTION! wear appropriate gloves and minimize your exposure to the vapors). •Place the glassware in a warm concentrated aqueous solution of Alconox, or other detergent, and let sit for several minutes. •Scrub. Be sure that your brush is in good shape before scrubbing (not rusty, bristles are not matted down); replace it if necessary. •Rinse thoroughly with tap water and give a final rinse with DI water. The water will sheet cleanly off the glass, if it is quantitatively clean. If water does not sheet off the glass, and you desire the glassware to be quantitatively clean, first repeat the above soaking and scrubbing steps. If, after a second cleaning, bits of solid still adhere to the glass, or if there is clearly a greasy residue on the glass, more aggressive action must be taken. More Aggressive Cleaning Methods For organic contaminant, submerge the item in a base bath (a saturated NaOH or KOH solution in ethanol or methanol). DANGER! The base bath will dissolve skin and alcohols are flammable! Wear butyl gloves and keep ignition sources away from the base bath. Be sure that the piece of glassware is completely filled with the solution and is sitting upright. After several minutes of soaking, carefully remove the item (it will be slippery), and rinse thoroughly. If the glassware is not quantitatively clean at this point, the general cleaning steps may need to be repeated, or a longer soaking time in the base bath, may be needed. NEVER soak the following items in a base bath for prolonged periods: Glassware contaminated with metal-containing compounds Glass fritted funnels Cuvettes Volumetric glassware (pipettes, volumetric flasks) Any glassware contaminated by an oxidizing agent Anything that has not been washed according to the above steps first Glass fritted funnels and volumetric glassware can be soaked briefly with the base bath solution to remove small amounts of grease, but prolonged exposure to the caustic solution can damage these items. -.ÅÆÒÓT U ’“¨©® ¯ di¿s“”OPjkisuvPTÒÖ [`§¨)*JKLWXÁÈr|ÀÅ ADòîáîÑîÇîÇîÑîÇîÇîÇîÑîÇîÑîÇáÇîÇºÇîÇîÇ¯ÇîÇîÇîÑŸÑÇ’ÇºÇáÇîÇîÇîh^&Ch^&COJQJ^Jh@ 56OJQJ\]^Jh^&C>*OJQJ^Jh^&C5OJQJ\^Jh^&COJQJ^Jh^&C56OJQJ\]^Jh^&C6OJQJ]^Jh^&Ch^&CCJOJQJ^JaJ9.ÆÓU “©¯ fiÁÄs”PkvQTÓÖ]`¨*KL÷òòòòòòéäéäéòòòòéäéäéäéòââgd^&C„Ð^„Ðgd^&Cgd^&C$a$gd^&CâþLÂÅCD[\fg›œÎÏâöñöéÜéÜéÜéÜéÜéÜö„Ð„x^„Ð`„xgd^&C &Fgd^&Cgd^&C„Ð^„Ðgd^&CDY\dg™œÌÏSZàâöòöòöòöòöòöçöòh^&C>*OJQJ^Jh^&Ch^&COJQJ^J21h:p€1Z°Ð/ °à=!°ð"°ð#ð$ð%°°Ð°ÐÐ†œ@@ñÿ@NormalCJ_HaJmH sH tH DA@òÿ¡DDefault Paragraph FontRi@óÿ³RTable Normalö4Ö l4Öaö(k@ôÿÁ(No ListB^`òB^&CNormal (Web)¤d¤d[$\$â(ÿÿÿÿ.ÆÓU“©¯fiÁÄs ” PkvQ T Ó Ö ]`¨*KLÂÅCD[\fg›œÎÏä˜0€€˜0€€˜0€€˜0€€˜0€€˜0€€˜0€€˜0€€˜0€€˜0€€˜0€€˜0€€˜0€€˜0€€˜0€€˜0€˜0€˜0€˜0€˜0€˜0€˜0€˜0€˜0€˜0€€˜0€€˜0€€˜0€€˜0€€˜ 0€€˜0€€˜ 0€€˜0€€˜ 0€€˜0€€˜ 0€€˜0€€˜ 0€€˜0€€˜ 0€€˜0€€˜0€€.ÆÓU“©¯fiÁÄs ” PkvQ T Ó Ö ]`¨*ÂÅCD[\fg›œÎÏäZÑ0ªZÑ0ªZÑ0ªZÑ0ªZÑ0ªZÑ0ªZÑ0ªZÑ0ªZÑ0ªZÑ0ªZÑ0ªZÑ0 €XÑ0€XÑ0€š@0€€€˜@0€€€˜@0€€€˜@0€€€˜@0€€€˜@0€€€˜@0€€€˜@0€€€˜@0€€€˜@0€€€š@0€€€˜@0€€€˜@0€€€š@0€€€š@0€€€š@0€€€š@0€€€š@0€€€š@0€€€š@0€€€š@0€€€š@0€€€š@0€€€š@0€€€š@0€€€ 0DâLââ%+8B›¡ÅÌ” › “—\dämxb{¸ º ä333--ÅÅ’’r r PÉÌáää$[aØ‘|ŽÿÿÿÿÿÿÿÿÿÐ„„˜þÆ^„`„˜þOJQJo(‡hˆHØðÐ„p„˜þÆp^„p`„˜þOJQJ^Jo(‡hˆHoÐ„@„˜þÆ@^„@`„˜þOJQJo(‡hˆH§ðÐ„„˜þÆ^„`„˜þOJQJo(‡hˆH·ðÐ„à„˜þÆà^„à`„˜þOJQJ^Jo(‡hˆHoÐ„°„˜þÆ°^„°`„˜þOJQJo(‡hˆH§ðÐ„€„˜þÆ€^„€`„˜þOJQJo(‡hˆH·ðÐ„P„˜þÆP^„P`„˜þOJQJ^Jo(‡hˆHoÐ„ „˜þÆ ^„ `„˜þOJQJo(‡hˆH§ð$[aÿÿÿÿÿÿÿÿ´Éd /|«Hœ?*iiOàjå@ ^&C€1Z :èÿ@€hh1ÇÇhhâP@ÿÿUnknownÿÿÿÿÿÿÿÿÿÿÿÿG‡z €ÿTimes New Roman5€Symbol3&‡z €ÿArial;€Wingdings?5 ‡z €ÿCourier New"qˆðÐhw{È¦{{È¦Å %Å %!ððð»´‚24ØØ2ƒQðHX)ðÿ?äÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ^&C2ÿÿ-The Grasshopper's Guide to Cleaning GlasswareGCCCDGCCCDþÿà…ŸòùOh«‘+'³Ù0˜˜ÐÜìø (4 T` lx€ˆä0The Grasshopper's Guide to Cleaning GlasswareGCCCDNormal.dotGCCCD1Microsoft Office Word@ @*ˆ.ÿÈ@B•½ÿÈÅþÿÕÍÕœ.“—+,ù®0hp€ˆ˜ ¨°¸ ÀúäGCCCD% Ø'.The Grasshopper's Guide to Cleaning GlasswareTitle þÿÿÿþÿÿÿ !"#$%&'(þÿÿÿ*+,-./0þÿÿÿ2345678þÿÿÿýÿÿÿ;þÿÿÿþÿÿÿþÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿRoot Entryÿÿÿÿÿÿÿÿ ÀFðÞµÎÿÈ=€Data ÿÿÿÿÿÿÿÿÿÿÿÿ1Tableÿÿÿÿ®WordDocumentÿÿÿÿ4(SummaryInformation(ÿÿÿÿÿÿÿÿÿÿÿÿ)DocumentSummaryInformation8ÿÿÿÿÿÿÿÿ1CompObjÿÿÿÿÿÿÿÿÿÿÿÿqÿÿÿÿÿÿÿÿÿÿÿÿþÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿþÿ ÿÿÿÿ ÀFMicrosoft Office Word Document MSWordDocWord.Document.8ô9²q