Charles Law Lab Report Essay Example

(voo) PROCEDURE Wear protective glasses. NOTE: It is essential that the Erlenmeyer flask and rubber stopper assemblvbe as drv as possiblein order to obtain reproducibleresults.

Dry a L25 mL Erlenmeyer flask by gently heating the entire outer surface with a burner flame. Care must be used in heating to avoid breaking the flask. If the flask is wet, first wipe the inner and outer surfaces with a towel to remove nearly all the water. Then, holding the flask with a test tube holder, gently heat the entire flask. Avoid placing the flask directly in the flame. Allow to cool. While the flask is cooling select a l-hole rubber stopper to fit the flask and insert a b cm piece of glass tubing into the stopper so that the end of the tubing is flush with the bottom of 66 the stopper. Attach a 3 cm piece of rubbertubingto the glass tubing (see Figure 19. 1-). Insert (wax pencil) the distance that it is inserted. Clamp the the stopper into the flask and mark flask so that it is submerged as far as possible in water contained in a 400 mL beaker (without the flask touching the bottom of the beaker) (see Figure I9. 2). Heat the water to boiling. Keep the flask in the gently boiling water for at least 8 minutes to allow the air in the flask to attain the temperature of the boiling water. Add water as needed to maintain the water level in the beaker.

Read and record the temperature of the boiling water. While the flask is still in the boiling water, seal it by clamping the rubber tubing tightly

with a screw clamp. Remove the flask from the hot water and submerge it in a pan of cold water, keeping the top down at all times to avoid losing air. Remove the screw clamp, letting the cold water flow into the flask. Keep the flask totally submerged for about 6 minutes to allow the flask and contents to attain the temperature of the water. Read and record the temperature of the water in the pan. Figure 19. Rubber stopper assembly Figure 19. 2 Heating the flask (and air) in boiling water t67 In order to equalize the pressure inside the flask with that of the atmosphere, bring the water level in the flask to the same level as the water in the pan by raising or lowering the flask (see Figure 19. 3). With the water levels equal, pinch the rubber tubing to close the flask. Remove the flask from the water and set it down on the laboratory bench. Using a graduated cylinder carefully measure and record the volume of liquid in the flask. Repeat the entire experiment.

Use the same flask and flame dry again; make sure that the rubber stopper assembly is thoroughly dried inside and outside. After the second trial fill the flask to the brim with water and insert the stopper assembly to the mark, letting the glass and rubber frll to the top and overflow. Measure the volume of water in the flask. Since this volume is the total volume of the flask, record it as the volume of air at the higher temperature. Because the same flask is used in both trials. it is necessarv to make

this measurement onlv once. Figure 19. 3 Equalizing the pressure in the flask.

The water level inside the flask is adjusted to the level of the water in the pan by raising or lowering the flask.