Tubing securing

When heating solids in a test tube, secure it in a clamp of a stand in an inclined position so that the mouth of the tube will be some-vrhat lower than its bottom (why ). First slightly heat the entire tube, and then more strongly the part where the solid is. 

Iron Sulphide. Prepare 5 g of a mixture of sulphur and a powder of reduced iron taken in equivalent amounts, transfer it into a test tube, secure the latter in the clamp of a stand, and heat the bottom of the tube on a strong flame until a reaction begins. As soon as this occurs, remove the burner. What is observed Write the equation of the reaction. How can you prove that the compound obtained is a sulphide Test the reaction of iron sulphide with hydrochloric acid. 

Pour 2 ml of concentrated nitric acid into each of five test tubes. Secure the first test tube vertically in a clamp of a stand and, while heating the acid, lower a glowing piece of charcoal into it. What happens Drop a piece of sulphur into the second tube secured in a clamp of the stand and heat the tube. When the tube cools, pour out its contents into water and detect the presence of sulphuric acid. Write the equations of the reactions. Heat the third tube with nitric acid and introduce a piece of wool into it. Comment on your observations. 

Preparation of Silicon Tetrachloride. To prepare amorphous silicon, mix 2 g of dry quartz sand comminuted in an iron mortar with 3 g of powdered magnesium. Spill the mixture into a refractory test tube, secure it at an angle in a stand, and carefully heat first the entire tube, and then its bottom end more intensively until the mixture ignites. When the reaction ends, break the test tube, extract the product, crush it, and wash it in a fume cupboard, wear eye protection. ) with dilute hydrochloric acid until the flashes of light vanish. Filter off the silicon, wash it on the filter with distilled water, and dry it in the air. 

Liquid ammonia is supplied in cylinders (Section 4.2.5, p. 417) which incorporate a simple tap valve with a screw-thread wide-bore outlet. Although a special gas-reducing valve may be obtained from the suppliers, for most purposes it is adequate to screw on to the outlet a wide-bore metal-tube adapter (Fig. 2.69(a)) to which may be fitted wide-bore rubber or stout polyethylene tubing, secured by copper wire. When the cylinder is upright only ammonia gas... 

After inserting a 21 /2-inch plastic straw segment into the aluminum tube piece, use long-nosed pliers to crimp one end of the tube securely. Keep the crimp short, neat, and pointed, as a clean point will facilitate insertion into the explosive mass later. 

Determining the Melting Point of Zinc Chloride Crystallohydrate. Put 1-2 g of zinc chloride crystallohydrate into a test tube, secure the latter in a clamp of a stand, and immerse it into a beaker with water heated to 40 °C. When the salt melts, introduce a thermometer into it (with graduations of 0.1 °C) secured in the stand clamp. Remove the burner and watch the dropping of the temperature. Write down the readings of the thermometer every 30 seconds. Use these data to plot the temperature against the time and establish the melting point of the zinc chloride hydrate. 

Place 100-125 ml of water in the Erlenmeyer flask and 2-3 boiling stones. Fit the stopper carrying the test tube securely into the... 

H) Preparation of Phenylhydrazones. Place 0.5 ml of benzaldehyde in a tube, and add 5 ml of phenylhydrazine reagent. Stopper the tube securely, shake the contents vigorously for 1-2 minutes, and allow to stand for 10 minutes, with occasional shaking. Filter the crystals with suction, and wash first with one per cent acetic acid and then with water. The yield is about 1 g. If it is desired to determine the melting point, the product is recrystallized from methanol or ethanol. 

Cut off about two feet of the bottom of the tubing and stick an end into the fawcet. Wrap a plastic baggy around the fawcet and the tube. Secure the tube by wrapping plastic tape around the fawcet, the baggy and a bit of the tubing. This will keep the water inside the tubing. 

Graphite Zone Liner. The graphite zone liner is the portion of the experimental hole liner which extends from the thermal shield to the reactor tank. It is a K-in.-thick aluminum tube secured at one end to the removable steel liner and supported at the other end by a pilot ring on the reactor tank. The liner is removable and is not permanently secured to the reactor tank because this tank is designed as a removable component. 

Taking Z = 11.0, the maximum diameter of the resonance tube securing... 

Pull a glass capillary tube. Secure the pipette horizontally on top of the microforge heating glass bead (Fig. lA). At an outside diameter (o.d.) of 80 fim (use a micrometric scale) slightly melt the pipette to the glass bead and turn off the heat. Pull the pipette horizontally to break the tip. To fire-polish the tip, secure the tip vertically on top of the bead. Turn on the heat and allow the tip to close off such that the inner diameter is 10 fim. 

Collect all the distillate in a 15-mL screw-cap centrifuge tube. Using a calibrated Pasteur pipette (see Experiment 1), add 2.0 mL of methylene chloride (dichlo-romethane) to extract the distillate. Cap the tube securely and shake it vigorously with frequent venting. Allow the layers to separate. Using a Pasteur pipette, transfer fhe lower mefhylene chloride layer to a clean, dry, 5-mL conical vial. Repeat this extraction procedure two more times with fresh 1.0-mL portions of methylene chloride and combine all the methylene chloride extracts in the same 5-mL conical vial that you used for the first extraction. If there are drops of water in the vial, it will be necessary to transfer the methylene chloride solution with a dry Pasteur pipette to another dry conical vial. 

Transfer tbe distillate to a 15-mL screw-cap centrifuge tube and add 1.0 mL of methylene chloride (dichloromethane) to extract the distillate. Cap the tube securely and shake it vigorously, venting frequently Allow the layers to separate. 

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