DRAFT: This module has unpublished changes.

Data Analysis

  

Parameter Trial 1 Trial 2 Trial 3 (run 5 on graph)
Mass of KHP (g) 0.2430 0.2791 0.2561
Number of moles of KHP (mol) 0.001190 0.001367 0.001254
Number of moles of NaOH  that can react the KHP (mol) 0.001190 0.001367 0.001254
Volume of titrant to reach the equivalence point (mL) 11.709 14.325 12.411
Concentration of NaOH solution (mol/L) 0.1016 0.09543 0.1010
Average concentration of NaOH solution (mol/L 0.09934 0.09934 0.09934

 

Calculations

 

 1. Number of Moles of KHP

 

Trial 1

Trial 2

Trial 3

2. Number of moles of NaOH

 Because the stoichiometric ratio between KHP and NaOH is 1:1, the number of moles of KHP equals the number of moles of NaOH.

 

3. Concentration of NaOH solution

 

Trial 1

Trial 2

Trial 3

4. Average concentration of NaOH

 

 Conclusion

      The purpose of this lab was to determine the concentration of a sodium hydroxide solution by titrating it with a standard solution of known concentration, KHP. Titration is a common technique that is used to determine the quantity of one reactant when the quantity of the other reactant is known. Once the solutions react in stoichiometric ratios the equivalence point is reached. The equivalence point tells the experimenters the volume of the unknown concentration of the reactant that is needed for the two solutions to react in a stoichiometric ratio. When the amount of solution added is stoichiometrically required there will be a large jump in the pH. That shows that the equivalence point has been reached. Once the volume of NaOH that is needed for the reactions to react in a stoichiometric ration is found, and the number of moles of KHP is known, the concentration of the NaOH solution can be found.

       The result of the lab was that the concentration of NaOH was 0.09934 M. This is pretty accurate since the desired concentration was to be close to 0.1 M of NaOH. NaOH is hygroscopic and it readily absorbs moisture from the air. This probably occurred during the lab while making the NaOH solution which lowered the molarity of the solution. A source of error in the experiment was not turning the magnetic stirrer on while titrating the solution which occurred in Trial 2 in the experiment. Because the magnetic stirrer was not on, the pH of the solution could not accurately be detected and remained at a constant pH of 4 for about 6 mL of NaOH that was titrated with KHP.  To improve this lab the experimenters need to make sure that all of the things necessary for the titration to run smoothly and correctly are working and turned on. Also some more runs of titration would make the concentration of NaOH more accurate.

DRAFT: This module has unpublished changes.