4. Never weigh chemicals directly on a balance pan. Use weighing paper, glassware, or other secondary container. 5. Waste solutions from this experiment should be disposed of in the appropriate waste container. PROCEDURE Part A Unknown Metal 1. Fill a 800-mL beaker with about 600 mL of water. Allow the water to adjust to room temperature. 2. Obtain a buret from your instructor and detach the tap and tip. Place a small rubber stopper at the 0.00 mL end of the buret. Invert the buret and fill to the 0.00 mL mark with water; do this slowly using your wash bottle or a pipet. Then pour the water into a clean 10-mL graduated cylinder. Measure the volume of water and record it in your lab notebook. This volume is known as V small . 3. Weigh about 0.02 g of a small strip of unknown metal using an analytical balance and record the mass in your lab notebook. 4. Using a piece of copper wire, approximately 15 cm in length, form a cage around the unknown metal at one end and a hook on the other end. CAUTION: Hydrochloric acid is caustic and corrosive. Avoid contact with skin and eyes. Avoid breathing the vapor. Make certain that you are wearing safety goggles, apron, and gloves when working with the acid. If any acid should splash on you, immediately flush the area with water and then report the incident to your teacher. If you should spill any on the counter top or floor, ask your instructor for the appropriate spill package to be used in the clean-up. 5. Using a 10 mL graduated cylinder measure 10 mL of 6.0 M hydrochloric acid solution from the dispensing bottle in the hood. 6. Make sure the stopper is secure at the zero end of the buret. Using your buret funnel carefully pour the 10 mL of 6.0 M hydrochloric acid solution into the buret. 7. While holding the buret in a slightly tipped position, very slowly add DI-water from your wash bottle into the buret, being careful to layer the water over the acid so that they do not mix. Add enough water to fill the buret to the brim. 8. Next lower the metal coil into the water in the buret so that it is attached by means of the hook. Insert the one hole rubber stopper into the open end of the buret to hold the copper wire in position. The one-hole stopper should displace some water from the tube. This ensures that no air is left inside the tube. You can use your wash bottle to fill the hole in the stopper so a bead of water forms on top. 9. Place a gloved finger over the top of the buret and invert it into the 800-mL beaker containg the water. Try to do this without allowing air to enter the buret by keeping your finger over the top of the buret until it is submurged in the beaker of water. Then relase your finger. Make sure the copper wire does not come loose.
4 10. Clamp the buret into position on the ring stand.
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