Aci dt 163 THER0368: Hear of Neutralization Na Saction Date Post-Laboratery Ques

Question

Aci dt 163 THER0368: Hear of Neutralization Na Saction Date Post-Laboratery Questiens he the spaces prorvided for the ansaers and additional paper if necessary.) 1. was given only one graduated cylinder to use for this experiment. After using it to measure 00 mL of the assigned acid, the student failed to.rinse or dry the cylinder before measuring out the 505 mL. of the base. Would the calculated AHneuten be higher, lower, or the same as the literature Hneutn Briefly explain this difference as a result of using only one graduated cylinder for the 5 experiment The aleutat ed AHneutzn would be kgies he ouse lower lot couse acid is low and since tne cyynder was not rias d risd i make tnebace become tower ne acid + oa? was (ovvb, ~ed by using only en- grodvated cyiader 2. Explain how the following changes in the procedure for this experiment would affect the results. (1) A glass beaker was used instead of a pressed polystyrene cup. A pressed polystyrene top was used to cover the polystyrene cup after the acid and base solutions had been mixed. (2)

Explanation / Answer

1. Enthalpy of neutralisation is the amount of heat released per mole of water produced (from neutralization). Higher enthalpy of neutralisation means that larger number of acid molecules are getting neutralised by equal number of base molecules resulting in more heat (exothermic process).Therfore,In this case calculated Enthalpy of neutralization would be lower than the literature value because when student used the cylinder for base measurements,that graduated cylinder already contain some amount of acid on its walls.so, the amount of base he measured is actually lower than the desired amount(50 ml).therefore, the amount of neutralisation would be lower than the case in which we use seperate graduated cylinder containing 50 ml acid &50ml base.

2.

1)In the experimental procedure if we use glass beaker instead of pressed polystyrene cup ,then measured heat of neutralisation would be lower than the literature(actual) value because whenever we measure enthalpy change of exothermic reaction we need thermal insulation for reaction mixture .so that heat of the reaction do not dissipate into the surrounding . Since glass is not a good thermal insulator,it causes dissipation of heat and we get lower value of enthalpy change than the actual one.

2)we need to use pressed polystyrene lid(top) to cover the polystyrene cup containing the reaction mixture(undergoing neutralization) to provide the complete thermal insulation from surrounding .By doing so we will get more accurate value of enthalpy of neutralisation experimentally(closer to the literature value).

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