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Unformatted text preview: HEAT OF NEUTRALISATION EXPERIMENT 1 DETEERMINATION OF ENTHALPY OF NEUTRALISATION OF ACIDS Date of experiment Team Role Name of Team Member Researcher Technician Safety Officer Data Analyst Introduction The heat of neutralisation of an acid by a case is the heat evolved when one mole of water is formed from the acid-base reaction: H + (aq) + OH- (aq) H 2 O(l) Chemical and physical changes are always accompanied by a change in energy. Most commonly, this energy change is observed as a flow of heat energy either into or out of the system under study. Heat flows are measured in an insulated instrument known as a calorimeter. As it is insulated, the calorimeter can effectively confine the heat energy transferred during a reaction and force it to bring about a change in the temperature or some other measurable property of the system. For example, the simple calorimeter you will use in this experiment is made of a heat-insulating polystyrene form material. The calorimeter for this experiment consists of two nested polystyrene foam coffee cup and a cover, with thermometer and stirrer inserted through holes punched in the cover. As you know, polystyrene foam does not conduct heat well and will not allow heat generated by a chemical reaction in the cup to be lost to the room. The initial temperature, that at which the reaction takes place, is represented by T 1 . T 2 is the final temperature for the system would have reached. Therefore, T 2-T 1 is the temperature change associated with the heat energy released by the reaction. The magnitude of this heat energy is given by: Heat energy (q) = C cal . (T 2-T 1 ) + m soln . C p(soln ) . (T 2-T 1 ) (Eq. 1) where, C cal : heat capacity of the calorimeter (J C-1 ) T 2-T 1 : temperature change ( C) M soln : mass of the solution in grams (g) C p(soln ) : specific heat capacity of the solution (J C-1 g-1 ) No calorimeter is perfectly adiabatic (one that does not exchange heat energy with its surroundings). Therefore, measuring the temperature change associated with the heat of reaction is complicated by a temperature variation caused by heat energy leaking into the coffee cup. Hence the heat capacity of coffee cup used as calorimeter will be determined before it is used for thermochemistry experiment....
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This note was uploaded on 10/17/2010 for the course FP- 034 taught by Professor Mdm.ting during the Three '10 term at Curtin.
- Three '10