Lab report Determination of Enthalpy Change of Neutralization

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Experiment 7

Determination of Enthalpy Change of Neutralization

Aim, introduction, apparatus and procedures refer to the instruction sheet.

Risk Assessments

    The thermometer used in the experiment is neither made up of alcohol or mercury. Both substances are harmful to our human body. Alcohol will catch fire quickly when it is in contact with fire or any flammable substance. Mercury is a poisonous and extremely toxic chemical. It can cause both chronic and acute poisoning. As a result, we must handle or use the thermometer carefully. Don’t use the thermometer as the gas rod to stir the solution. If the mercury or alcohol is spilt out from the thermometer, we must leave the area of alcohol or mercury and then call the teacher immediately as we don’t know how to clean the mercury or alcohol at our level.

    Secondly, hydrochloric acid used in the experiment is corrosive although it is diluted. It can hurt our skin and irritate our eyes. Therefore, we should handle it very carefully. If the acid is spiller out and fell on our skin or eyes, we have to wash the infected area with plenty of running water or eye wash bottle. Moreover, the hydrogen gas produced from the reaction between calcium and hydrochloric acid is flammable. Explosion will occur if there is fire. As a result, we should keep the experiment away from the fire and conduct the experiment under the good ventilation condition.

Results & Calculations

Mass of thermometer = 20.73 g = 0.02073Kg

Mass of glass rod = 22.34 g = 0.02234 Kg

Mass of plastic beaker = 2.28 g = 0.00228 Kg

Length of the thermometer = 29 cm

Length of the glass rod = 26 cm

The length of thermometer and glass rod immersed = 3 cm

To calculate the enthalpy of neutralization of the above six neutralization, we can make use of the following formula,

Heat evolved = (m1c1 + m2c2) * Temp. Difference

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Enthalpy change of neutralization = energy / no of mole of water formed

Assume:   1.) 1 cm3 = 1 g for the calculations of the six reactions below.

2.) Specific heat capacity of acid & alkali = 4200 J Kg-1K-1

3.) Specific heat capacity of glass = 840 J Kg-1K-1

4.) Specific heat capacity of plastic beaker = 0 J Kg-1K-1

Reaction 1:

Mass of the solution = (25 + 25) /1000 = 0.05 Kg

Heat given out = (0.05 * 4200 + (3/29 * 0.02073 + 3/26 * 0.02234) * 840) * 12.0

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