Towels and Wipes

The increasing use of disposable paper towels and wipes in chemical laboratories accentuates the potential fire hazards arising from the disposal of solid oxidising agents or reactive residues into a bin containing such towels or wipes. The partially wet paper, necessarily of high surface area and absorbency, presents favourable conditions for a fire to be initiated and spread. Separate bins for paper towels etc., and chemical residues seem advisable. 

Use the disinfectant solution according to the manufacturer s directions to thoroughly clean and disinfect your work area. Wipe the area with paper towels and dispose of the towels as directed by your teacher. Wash your hands with antibacterial soap. 

When all the violet dye is off the column, begin to collect and evaporate 10-ml. fractions. Two or three fractions, which on evaporation yield little or no residue, will precede the appearance of the 7-benzene hexachloride. Continue to collect 10-ml. fractions and evaporate until no more 7-benzene hexachloride is obtained. Stop the column operation, dissolve the several 7-benzene hexachloride residues with a minimum quantity of n-hexane, and pour into a tared 125-ml. Erlenmeyer flask. Evaporate under vacuum, using the solvent evaporator, at 60° and finally at room temperature for 5 minutes with a high vacuum pump. Release the vacuum, wipe the flask with a clean, moist towel, and weigh after allowing the flask to come to equilibrium near the balance. Calculate the percentage of 7-benzene hexachloride in the original sample. 

Place emulsion-coated slide in a horizontal position and wipe the back of the dipped slide with a paper towel or a damp sponge and place the slide flat on a drying rack protected from safelight exposure for 1 h at 45-50% relative humidity (RH). The emulsion will gel in approximately 1 h but can be speeded up by placing the slide on a cold metal plate for 15-... 

Step 6 Keeping your index finger in place, remove the tip from the solution and wipe with a towel. To avoid... 

The dry copper can be placed in a waste container. Wet any residue that sticks to the beaker and wipe it out using a paper towel. Pour the unreacted copper(II) sulfate and iron(II) sulfate solutions into a large beaker in the fume hood. 

The gas inlet tube is replaced by a dropping funnel protected by a calcium chloride drying tube. Isocaproyl chloride (84.7 g., 0.63 mole) (Note 5) is added to the reaction mixture with stirring over a period of 20 minutes. The dropping funnel is replaced by the gas inlet tube (inlet tube wiped with a dry towel), and, with stirring, acetylene is bubbled just below the surface of the mixture at a rate noticeably above the saturation rate. After 15 minutes to 1 hour the rate of absorption of acetylene suddenly becomes very rapid, and the acetylene is passed through as rapidly as it is absorbed (Note 6). The introduction of acetylene is continued for 30 minutes after the rapid absorption (which lasts 1-2 hours) has subsided. 

Clean and remove electrostatic charges from the solution tubes by wiping them with a wet towel and drying them with a clean lint-free cloth (without tubbing). Place the tubes in the wire-screen tray, cover them with a cloth to protect them from dust, and allow them to stand near die balance for at least 30 mins to attain equilibrium with the moisture content of the air... 

In a 250-00. Erlenmeyer flask provided with a two-holed stopper which has a slit cut in one edge to serve as an air vent and which holds a thermometer, the bulb of which reaches almost to the bottom of the flask, is placed 31.5 g. (0.5 mole) of anhydrous nitric acid (Note 1). The flask is cooled below io° in ice-water, and 51 g. (0.5 mole) of acetic anhydride (Note 2) is slowly added from a buret through the second hole in the stopper in portions of about 0.5 cc. at a time. The temperature of the reaction mixture is never allowed to rise above io° (Note 3). After about 5 cc. of the acetic anhydride has been added the reaction becomes less violent, and larger portions, increasing gradually from 1 to 5 cc., may be introduced at a time with constant shaking. After all the acetic anhydride has been added, the stopper and the thermometer are removed. The neck of the flask is wiped clean with a towel, and the flask is then covered with an inverted beaker and allowed to come up to room temperature in the original ice bath (Note 4). 

Another demountable cell is pictured in Fig. 4. The plates are thin wafers of silver chloride, which is transparent to infrared radiation. This cell has advantages over the salt cell in that the silver chloride disks are more resistant to breakage than NaCl plates, they are less expensive, and they are not affected by water. Because silver chloride is photosensitive the wafers must be stored in the dark to prevent them from turning black. Because one side of each wafer is recessed, the thickness of the sample can be varied according to the manner in which the cell is assembled. The disks are cleaned by rinsing them with an organic solvent such as acetone or ethanol and wiping dry with an absorbent paper towel. 

All the vials are placed in the dark for at least 5 min, removed, and wiped with a clean, damp, paper towel and placed into a scintillation counter. Counts ... 

Wipe the outside of the box with a dry towel and weigh immediately. Record the weight of keen box plus filter paper and saturated soil. 

Perform this test with the help of your supervisor. Place 1 drop of the solution labeled N03 in a cuvette. Add 1 drop of 0.1 M HC1 and fill to the top with distilled water. Shake. Nitrate strongly absorbs ultraviolet light at 220 nanometers (nm) under these conditions. Wipe the exterior of the cuvette with a paper towel, and place it in an ultraviolet (U V) spectrophotometer set at 220 nm. A high absorbance reading represents a positive test for nitrate. Compare with distilled water. 

Safety Note When touching the material, students should put a small amount between their fingers and observe it over the tray or on it. Help students understand never to touch an unknown chemical unless they are told it is safe. Ask students to use paper towels to wipe their hands. 

Have the class clean up by returning the trays, cups, and goggles (placed in their labeled plastic bags) to the materials center. Ask students to throw away the sealed bags of goo and the paper towels and to wipe desks clean. 

Refer to Figure E36-I. It can all be set up on one ring stand. The apparatus often will become covered with a white solid. This is ammonium chloride and will wipe away easily with a wet towel and is not harmful. 

Wipe the spoon with a clean rag or paper towel and place one measure of potassium dlilorate into the boiling sugar water. 

Use as is in spray trigger spray bottle. Spray on and wipe off with clean cloth or paper towel. 

Apply finished product to a towel or towellete (Kimwipe, etc.) and wipe onto the surface to be cleaned, then rinse. Alternatively, spray onto the surface to be cleaned, allow to set a few minutes, then rinse or hose off. 

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