Molar Enthalpy of Reaction

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Evaluating experimental designs and estimating the certainty of empirically determined values are important skills in interpreting scientific statements. The purpose of this exercise is to test the calorimeter design and calorimetry procedure by verifying a widely accepted value for the molar enthalpy of a neutralization reaction. The accuracy obtained in this investigation is used to evaluate the calorimeter and the assumptions made in the analysis, not to evaluate the prediction and its authority, The CRC Handbook of Chemistry and Physics. The ultimate authority in this experiment is considered to be the reference value used in the prediction.

Problem

What is the molar enthalpy of neutralization for sodium hydroxide when 100 mL of aqueous 1.0 mol/L sulphuric acid with  an excess quantity of 1.0 mol/l sodium hydroxide?

Procedure

Use the interactive tool below to calculate the molar enthalpy of neutralization for the various acids and bases listed.
1. Pick the appropriate acid and base for each tank.
2. Set the molar concentration and volume for the acid in Tank A.
3. Calculate the needed quantity of a 1.0 mol/L sodium hydroxide to neutralize the acid.
4. Set the molar concentration and volume of the base in Tank B.
5. Record the initial and final temperatures after the solutions are mixed.
6. Repeat the procedure with acetic acid neutralized by sodium hydroxide and hydrochloric acid neutralized by sodium hydroxide.
 

 


Chemical Education Research Group, Iowa State University, Ames IA

Evidence Table

Acid Initial Temp. (C) Final Temp. (C)
Sulphuric    
Acetic    
Hydrochloric    

Analysis

1. Write a balanced chemical equation for the neutralization of each of the following acid-base combinations.

bulletacetic acid with NaOH
bullethydrochloric acid with NaOH
bulletsulphuric acid with NaOH

2. Calculate the change in temperature for each of the neutralization reactions.

3. Calculate the molar enthalpy of neutralization for each acid.

4. Write the reaction including the enthalpy of reaction.

5. Rank the molar enthalpy changes from lowest to highest. Account for the differences.