inflotion fighter1 The Aladdin Lamp Caper Sheldon H. Cohen Washburn Universiv Topeka, KS 66621
In this time of tight money, all of us would be happy to accept a n offer of new equipment for our old broken-down apparatus. Unfortunately, if we remember a similar offer from the Arahian Nights, this type of transwtion may not always he hased on the highest of moral prinriples. In this column three ways nt'acmmplishing this rniraculm~strnnsfurmation wit hout the pruverl~ialgenie will he discussed. Our stockroom contained agreat many rusted forceps and tongs. Because of their appearance students would not or could not use them. Instead of buying new ones, the simple solution was to clean them. Our sintered crucibles began to filter slower and slower. Instead of replacing them, the solution was again reconditioning. Rust Removal Because of the conditions in the chemistrv laboratorv. .. ao. paratus made of iron frequently acquire a heavy coating of rust. I n most cases, the item can still function in a ~ e r f e c t l v effective manner, but because of its appearance, i t i s store; forever in an out-of-the-way drawer. There are as many ways to remove rust as there are people doing it. Commercial rust removers can be purchased, hut they are relatively expensive. A number of inexpensive effective sohitions can easily be made in the laboratory. A few that I have used are given below. (1) A solution of about 2 thsp of ammonium citrate crystals in 1
1of water. The proportions are not critical, and the solution can be used repeatedly until it is depleted. The rusted items are placed in the hot solution and left for at least 1hr. If the solution is used cold, an overnight soaking is needed. The results are god, but the rust is not removed as efficiently as in the next two procedures. (2) A one-to-one solution of phwphorie acid and water. Technical grade phosphoric acid is mixed intoan equalvolume ofwater. Iron forceps which are completely covered with corrosion are cleaned of all rust with a 15-min boiling in the solution. Although this method is quick and efficient, it has the major disadvantage of producing a large amount of hydrogen after the iron oxide has reacted. This can be prevented by removing the iron item from the solution as soon as it can be seen that the rust is removed. A water rinse and an air-dryingleaves the apparatus ready to use. (3) Concentrated phosphoric acid. The last method is the old standby. The corroded items are dipped into concentrated phosphoric acid. All parts of the metal must be exposed to the liquid. The acid is allowed to drain from the metal, and it is hung up to dry for at least 12 hr. After this time, the acid is washed off with water. and the metal is finallv air-dried. Most items are cleaned of rust in one dipping, buifor very heavily corroded pieces two dippings will be needed. Caution: proper safety procedures must b e heeded w h e n working w i t h concentrated solutions of acids (procedures t a n d 3 above). Cleaning of Cruclbies Filtering crucibles with sintered glass - disks have become very cnmmon pieces of equipment for doing gravimetric experiments. Since each crucible costs nearh eipht dollars, it is important to be able to reuse them contin"ou&. After few
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670
Journal of Chemical Education
edited by SHELDON H. COHEN
Washburn University Topeka.Kansas66621
experiments, the flow rate of the solution through the disk zeta so-slow that the crucible is no longer useful.- he two most common solids which clog the sinter are silver chloride and barium sulfate. A procedure which works well for the silver salt is first to remove the cake of silver chloride mechanically, and then soak the crucible for ahout twenty minutes in concentrated ammonia. (Caution: make s u r e t h i s is done i n a hood.) Place the crucible into a holder on a suction flask and rinse with water under vacuum. Use distilled water for the final rinse. If after rinsing the sinter disk is dark, empty the suction flask and draw a few milliliters of concentrated nitric acid through the crucible. Rinse thoroughly and the crucible is ready touse again. Barium sulfate solid is more difficult to clean from the sintered disk than the silver chloride. A successful nrocedure is tosoak the crucible in a hoiling sodium carbonaie solution (40 r of carbonate uer 100 ml of water) for about 20 min. Rinse the&ucihle with water after draining the carbonate solution. Place the crucible into 6 N hydrochloric acid and again rinse with water. Afew portions of the 6 N HClsolution are drawn through the crucible under suction, and this is followed by a water rinse. With the present cost of new apparatus, any reuse of old equipment will amount to a healthy savings. If you have a favorite recycling process, please share i t with us.
Inexpensive Alternate Chemical Sources Joseph M. Stefanko Central High School West Aliir. WI 53227 As a high school chemistry teacher, I have become very concerned with budget expenditures. Since our school budget is based on the number of students enrolled, declining enrollments mean a decreasing budget, even though inflation has increased our supply costs. Thus, we have been looking to other sources of supply. In many experiments it is not necessary to use reagent-grade chemicals. Here are some of the adjustments we have made. 1) Marble chips are used to produce COs Nursery supply stores and
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some hardware stores sell a white decorative stone. These are marble chips of good quality. Elemental sulfur is needed ina number of experiments. Sulfur is available in 50-lb hags from industrial suppliers. This is good quality sulfur and can be purchased at about 20%of the cost from chemical supply houses. Sodium chloride is needed in such experimentsas the production of hydrogen chloride gas. The salt sold for the recharging of water softener resins is of good quality and is available in many grocery stores, especially thwe located in areas where people have private wells. Zinc is used in the generation of hydrogen gas. We contacted a local galvanizingplant and bought 100lb at about 20% of the chemical supply house cost. Lead is sold as'sheetingin many hardware stores, as is copper. A Memods and details of how you can save money by building your own equipmentareanlined in this featwe. M you have made sawing which is particularly useful or money saving, please share it with our readers.
