# The initial temperature of the naoh solution was 469

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temperature of the solution. The initial temperature of the NaOH solution was 46.9 C and the ̊ final temperature was 23.9 C. Using this information, the mass and the specific heat capacity ̊ of the solution, the molar enthalpy was calculated. The molar enthalpy of NaOH assuming no

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heat lost is -100085.1 J/mol and the molar enthalpy of NaOH including heat lost to calorimeter (by using calorimeter constant calculated in part B) is -101391.5 J/mol. The heat capacity of the solution is assumed to be approximately that of pure water, 4.184 J/g* º C. In the second part of the experiment, ∆T for both heated water and cool water was calculated, -10.2 º C and 7 º C respectively. Using ∆T and the mass of the hot water and cold water, the calorimetry constant was calculated as 0.0142 KJ/ º C. Using that, the specific heat capacity of the calorimeter was determined: 0.24J/ º C*g. In the third part of the experiment, the NaOH concentration was determined in three different ways, giving us three different values: 1mol/L, 0.428 mol/L and 0.432 mol/L. The second and third values of the concentration of NaOH were similar, but they were both not similar to the first value. Besides, 0.107 mol of H 2 O are formed from this condition and the molar concentration of the original solution is 1.07 mol/L. The results are accurate compared with theoretical values. The deviation can be explained by errors that occurred in the experiment. The apparatus used for this experiment is a calorimeter in which a thermometer was inserted to determine the temperature of the solution or water. The apparatus and method were effective, however, little errors might have occurred: heat might be escaped when the lid was removed to add other solutions to the calorimeter. Conclusion In conclusion, the purpose of this lab is to use calorimetry to determine the unknown concentration of sodium hydroxide after it is neutralized with hydrochloric acid. The purpose
was achieved and the molar concentration of sodium hydroxide was calculated in three different ways: using the moles of NaOH and the volume of water or using calorimetric datas. The molar concentration of NaOH was calculated to be 1 mol/L according to the first method, 0.428 mol/L according to the second method assuming no heat is lost, and 0.432 mol/L according to the third method including heat lost. All three answers were different, this could have been a result of experiential errors like heat loss or inaccurate temperature measures which lead to inaccurate results. Overall, using calorimetry for this experiment was effective and the results were accurate.

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References Department of Chemistry (2019). Chemistry 123L Winter 2019 Lab Manual. Waterloo, ON: University of Waterloo. (pp. 29-35)

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