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Study on Physical Chemistry Lab

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Added on  2020-05-08

Study on Physical Chemistry Lab

   Added on 2020-05-08

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Running head: PHYSICAL CHEMISTRY LAB 0PHYSICAL CHEMISTRY LABName of the student.Institutional affiliation.
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PHYSICAL CHEMISTRY LAB 2TITTLE: HEAT OF COMBUSTION AND ADDITIVE ERRORS VIA PROPAGATION OFERRORS TECHNIQUE.Preparing the pellet:Procedure A sample of Benzoic acid of 1 to 1.2 grams was weighted. The sample cap was pre-weighted. The instructions given below was followed using the figure 5.1; The die was set over the receiving cap with three parts resting on the base of the press. The plug was dropped into the die.The die, cup, and plug were transferred onto the anvil while holding one finger against the bottom of the cup to keep it and the plug in place. The die was filled with the roughly weighed sample. The charge was compressed by pushing the lever down. The die was raised or lowered by screwing the anvil up or down until firm pressure was acquired to push the lever through its full stroke (Paula, J. 2010). The lever was raised, the die was slid from the anvil and the cup and plug removed. The cup and die were returned to their original position on the anvil and the plug was gently dropped into the top of the anvil above the pellet.The level was brought down gently to eject the pellet into the cup. Care was taken not to move the level through a full stroke to avoid crushing of the pellet. The lever was raised and parts slid from the anvil. The pellet cup was taken and weighed accurately on balances. Handling of the cup with fingers was avoided as much as possible.The cycle was repeated starting at step 1 for each pellet required.CHARGING THE BOMBProcedureThe huge knurled cap was taken out of the bomb and the inside part of the bomb wascarefully extracted and put on the special holder provided.The already weighed-sample and
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PHYSICAL CHEMISTRY LAB 3cup were placed in the yoke.An ignition wire that had already been cut was used to securelytie each arm of the electrodes allowing a loop between that ensured the wire touched thesurface of the pellet. Caution was taken or ensure it did not touch the sides of the metal cup.All parts assembled were put on the lower part of the bomb and pressed down ensuring thatthe O-ring had fitted well (Bettelheim.F.A. 1971). The knurled cup was tightened making ithand tight.NOTE: it was inevitable for the electrode connections to be placed at 90° from theholes in the cap to facilitate clearance of the electrodes by means of the transport clamp afterconnection.CHARGING THE BOMB WITH OXYGEN.The hose was attached from the regulator on the oxygen tank to the head of thebomb.The safety valve on the bomb was opened by turning the knurled knob to the left 1-2times.The cylinder was opened by turning the cylinder valve. The valve was not openedcompletely. The small knob on the regulator that was black was turned to allow gasmovement into the bomb very slowly. The large gauge on the regulator was watched.Thebomb was supplied with oxygen for about 15 seconds. The knurled knob was turned down onthe safety valve and pressure in the bomb was allowed to build up to about 25 atmospheres.The regulator knob was quickly closed. It was necessary that the pressure in the bomb did notexceed 30 atmospheres.The black lever found below the regulator knob was depressed andany pressure in the line of the bomb was released. A one-way valve in the bomb preventedpressure loss (Reid, P. (2013.)). The hose connection to the bomb was unscrewed and the bombwas carefully placed out of the way of the bench top.
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PHYSICAL CHEMISTRY LAB 4Adjusting the controller.The hot and cold water taps were fully turned. At the top of the Calorimeter. The balance knob was turned to O position. The jacket temperature control was turned to minimum. The switch was turned to run position. The power switch was turned on. The controller was run for about 5 minutes to realize some extent of equilibrium. When stabilizing the controller, the stainless still container was filled with deionized water: The weight of the dry container was tarred off and recorded. 20000.2g of deionized water was added to the container (Reid, P. 2013.). The temperature was checked with a lab thermometer so that it lied between 19.5 g to 21°C. This was placed in a calorimeter so that it sat on the proper pins in the bottom of the cavity. The special wire holder was used to lower the bomb part way into the water. The leads were attached to the electrodes and slowly lowered the bomb into the water so that it settled on the raised portion of the container. The clamp was removed from the bomb and anywater droplets that would have adhered into the clamp were shaken off. The thorough scrutiny was done to ensure there were no bubbles, an indicator that there would have been a leak in the bomb assembly. The cover of the calorimeter was closed and the thermometer waslowered and stirred into position. The solution was allowed to attain equilibrium for about 5 minutes. The temperature on the bucket thermometer was read to discover fluctuation. After the temperature had stabilized, the balance knob was adjusted until the jacket temperature was exactly the same as the container. This had to be done slowly to avoid overshooting the jacket temperature. As the two temperatures approached each other, the white and orange lights interchanged on and off. When the container and jacket temperatures were same, the balance knob was locked and read with the magnifier. The container temperature was measured to the nearest thousandth
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