Test tube rack, making

Attach the glass U-tube to the loose end of the rubber tubing. Fill the 1-L beaker with water. Fill three 20 x 150-mm test tubes with water, and place them in the test tube rack. Make certain that three 2 solid rubber stoppers are close at hand. Place your thumb over the first test tube, and invert its mouth under water in the beaker without allowing any air to enter. Then insert the glass U-tube into the test tube as shown in FIGURE 38.2, and allow the assembly to rest on the bottom of the beaker. 

How can you make a polyester and a polyamide Objectives Prepare a polyester from phthalic anhydride and ethylene glycol. Prepare a polyamide from adipoyl chloride and hexamethylenediamine. phthalic anhydride (2.0 g) sodium acetate (0.1 g) ethylene glycol (1 mL) 5% adipoyl chloride in cyclohexane (25 mL) 50% aqueous ethanol (10 mL) 5% aqueous solution of hexamethylenediamine (25 mL) 20% sodium hydroxide (NaOH) (1 mL) scissors copper wire test tube test-tube rack 10-mL graduated cylinder 50-mL graduated cylinder 150-mL beakers (2) ring stand clamp Bunsen burner striker or matches balance weighing papers (2)... 

Follow this procedure Label 5 test tubes 1 to 5 or label their places in the test tube rack. Fill these 5 test tubes halfway with warm water. Put teaspoonful of sodium chloride into the first test tube, i teaspoonful of talcum powder into the second, and so on, for the next three substances. Do not use the potassium aluminum sulfate yet. If the substance doesn t dissolve right away, heat the test tube over the alcohol burner until it does, or until you are sure it won t. Make out a data sheet similar to this one ... 

Dry the rack of test tubes, the vials, and caps needed to make the stock solutions at 100°C for 16 h (overnight). Predried vials and caps must be used in subsequent steps. 

With the eye dropper, add some soap solution, drop by drop, to test tube No. 1, shaking the tube very hard between drops. Count how many drops are needed to make suds and record the number. To test tube No. 2, add some soap solution in the same manner and count again. To test tube No. 3, add some soap solution in the same way. Take test tube No. 4 from the rack and boil the liquid over the alcohol flame. Add some soap solution after it has cooled, and count the drops needed to form suds. To test tube No. 5 add soap solution only, shake, count the drops, and record the result. To test tube No. 6 add 1 teaspoonful of sodium tetraborate or potassium carbonate, then add some soap... 

Follow this procedure Set up the test tubes in the racks and label each one with one of the chemical names listed above. Put teaspoonful of each chemical into the correct tube. Add enough water to fill the tubes to approximately 1/3 their height. Make a data sheet similar to the one here, and as you proceed, fill in the spaces. 

Place the test tubes in the rack in a sequence that will make it convenient and accurate to collect fractions. Allow them to cool to ice water temperature. 

To set up compounds for toxicity treatment For each compound, a total of four concentrations will be examined. This will require nine sets of four sterile, 1.1-mL minitubes (36 tubes/compound). Into the first tube of each set, aliquot sufficient compound to make up 465 pL of the highest test concentration. Leave the other tubes empty. Cover the tubes with the rack lids, and store the racks at -20°C or at an appropriate temperature. Tubes for the last day of treatment for toxicity testing contain the same amount of compound as used the previous days (not 3X as for the antiviral assays). 

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