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Experiment 9 Report sheet

Tared mass of KHC8H4O4 Molar mass of KHC8H4O4 Moles of KHC8H4O4 Buret Reading of NaOH

Trial 1 .4865 204.23 .00238212 19.99

Trial 2 .4472 204.23 .00218969 19.62

initial (mL) Buret Reading og NaOH

30.69

29.63

final (mL) Volume of NaOH dispensed

10.70

10.01

(mL) Molar Concentration of

.2226

.21896

NaOH (mol/L) Average Molar

.2208

concentration of NaOH (mol/L)

Experiment 10 Trial 1 84.68 102.01 17.33

Trial 2 94.36 113.18 18.82

sample Buret reading of NaOH

29.61

28.55

initial (mL) Buret reading of NaOH

40.38

35.73

final (mL) Volume of NaOH used (mL) Molar concentration of

10.77 .1

7.18

Mass of Flask (g) Mass of flask + vinegar (g) Mass of vinegar (g) B. Analysis of vinegar

NaOH (mol/L) Moles of NaOH added (mol) .00108 .00108 Moles of CH3COOH in

.00072 .00072

vinegar (mol) Mass of CH3COOH in

.06485

.04312

vinegar (g) Percent by mass of

.6021

.6006

CH3COOH in vinegar (%) Average percent by mass of

.6013

CH3COOH in vinegar (%) Discussion: This experiment was executed to determine the molar concentration of NaOH and the average percent by mass of acetic acid in unknown solution Dallas using titration analysis. As we know, titration analysis is the process of chemical analysis that is performed primarily with the help of volumetric glassware like pipettes, burets and volumetric flaks. For a volumetric analysis procedure, a known quality or a carefully measured amount of one substance reacts with a to-bedetermined amount of another substance with the reaction occurring in aqueous solution. For the

acid-based titration studied in experiment 9, the titrant is a standard solution for sodium hydroxide analyte is KCH8H404. In experiment 10, the titrant is a standard solution of sodium hydroxide. The reaction is complete when the stoichiometric amounts of the reacting substances are combined. In a titration, this is the stoichiometric point. In both experiment 9 and 10, the stoichiometric point for the acid-base titration is detected using a phenolphthalein indicator. In experiment 9, the sodium hydroxide solution was standardized with potassium hydrogen phthalate (KCH8H4O4) which is a white, crystalline, acidic sloid, which contains the properties of a primary solution and this is due to its high acidic status. In our experiment, we looked at different aspect with CH3COOH. We determined that the volume of the reactant was 10.7 mL causing for the moles of NaOH added result in .2226 mol. Conclusion: The purpose of this experiment was to be able to standardize the sodium in a NaOH solution. The molar concentration of a strong acid was determined throughout this experiment. In order to conduct these direct-related experiment, gravimetric analysis and volumetric analysis was necessary with the use of titration. In experiment 9, it was heavily focused on the KHC8H4O4. In experiment 10, the known substance Dallas was used to determine the percent mass of acetic acid (CH3COOH) in vinegar. Post Lab questions Experiment 9 4. Water is added because the precipitate needs to be dissolved, hence the addition of water does not matter in the case of KHC8H4O4, while in case of NaOH, water added to it dilutes the base and changes the molarity. Also, water added to the flask dilutes the sample BUT it dilutes the NaOH being added by the same amount.

6. The consistently dark pink color change will result in the molar concentration of the acid being too high. This is because the darker pink the solution became, the more NaOH was needed to turn the acid basic, therefore the acid was very acidic. The darker the pink, the higher the molar concentration of the acid. Experiment 10 5. This technique increases the reported acetic acid in the vinegar because the person should have waited the 10-15 seconds before recording the initial volume of the buret. If the person did this, they would have accurately found the difference between the two measurements, which is the NaOH used.

References Beran, J. A. (2014). Laboratory manual for principles of general chemistry. Hoboken (N.J.): Wiley....