Calorimetry Post Lab (10 pts) An experiment is to be performed to determine the

Question

Calorimetry Post Lab (10 pts) An experiment is to be performed to determine the standard molar enthalpy of neutralization of a strong acid by a strong base. Standard laboratory equipment and a supply of standardized 100-molar HCl and standardized 1.00-molar NaOH are available (a) What equipment would be needed? Page reference (b) What measurements should be taken? Page reference (c) Without performing calculations, describe how the resulting data should be used to obtairn the standard molar enthalpy of neutralization. (d) When a class of students performed this experiment, the average of the results was -55.0 kilojoules per mole. The accepted value for the standard molar enthalpy of neutralization of a strong acid by a strong base -57.7 kilojoules per mole. Propose two likely sources of experimental error that could account for the result obtained by the class.

Explanation / Answer

a) Equipment needed to perform an experiment:

1) Colorimetry equipped with thermometer

2) burrete for an addition of acid/base

3) magnetic stirrer for mixing of reaction mixture

b)

1) initial temperature of reaction mixture(without addition of HCl)

2) final temperature of reaction mixture ( after addition of HCl)

3) total volume HCl added

c)

Neutralisation reaction is reaction between acid and base to produce water molecule

therefore, standard molar enthalpy of neutralisation reaction is equal to heat of formation of water.

which is equal to -57.7 kj/mole

d)

1) Extra drop of HCl leads to give wrong final temperature. Because addition of extra drop gives lower temperature than actual temperature.

2) Calibration of thermometer

3) The assumption we made,for specific heat of reaction mixture is equal to specific heat of water.

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