Prietha.Thavakumaran.Experiment3

SC/CHEM 2080: Analytical Chemistry Experiment 3: Acid-Base Titration Using An Indicator – Analysis of an Unknown Base Prietha Thavakumaran TA: Lisa Azzarello Date Performed: Thursday, October 19 th , 2023 Due: Friday, October 27 th , 2023

2 Abstract An acid-base volumetric titration was performed using a primary standard acid, KHP with an acid-base indicator to determine the concentration of an unknown base of NaOH (York, 2023). Three replicates were created, and the average volume delivered was 17.8 mL with a standard deviation of 0.0898 mL. Results Table 1. Acid-Base Titration Data: Observed and Calculated Unknown NaOH KHP Unknown #282 Initial Volume (mL) Final Volume (mL) Total Volume (mL) Concentration (mol/L) Volume of KHP (mL) Mass of KHP (g) M. W. (g/mol) *Moles (mol) *Concentration (mol/L) - - - - - 5.1068 204.2223 0.025006084 1.00024336 Trial 1 10.399 28.125 17.726 *1.410700891 25 - - - - Trial 2 13.6115 31.379 17.7675 1.407405882 25 - - - - Trial 3 12.601 30.499 17.898 1.397144038 25 - - - - Average 12.20383333 30.001 17.79716667 1.405083604 - - - - - Standard Deviation 1.64266402 1.683191017 0.089755687 0.007070488 - - - - - *Uncertainty - - - 0.003653217 - - 0.002 - 0.002194776 *95% Confidence Interval - - - ±0.017565483 - - - - - Three replicates were made and produced a mean of 17.8 mL ± 0.0898 mL (n=3). The average concentration of the unknown was 1.40 M ± 0.00365 M (n=3). *Sample calculations can be found in the Appendix. Three replicates were made and presented an average volume of 17.8 mL ± 0.0898 mL of an unknown NaOH. Furthermore, an average concentration of 1.40 M ± 0.00707 M was calculated with an uncertainty value of 0.00365. Equally important, a 95% confidence interval was calculated as ± 0.01757 M. Likewise, the concentration of KHP was calculated as 1.0024 M with an uncertainty value of 0.00219. Discussion The results of the experiment indicated that the average volume of the unknown NaOH delivered was 17.78 mL ± 0.0898 mL. The standard deviation suggests that the replicates are close in distribution and are accurate as well as precise as they approach the mean value.

4 transitions from acidic (colourless) to slightly basic (pink) as the titration reaches its equivalence point (Harris et al., 2020). Appendix Sample Calculations: Concentration of KHP Mol = mass/M.W. = 5.1068 g / 204.223 g/mol = 0.025006084 mol [KHP] = mol/vol = 0.025006084 mol / 0.025 L = 1.00024336 mol/L Uncertainty of [KHP] e = x ! ( !" " ) # + ( !$ $ ) # = 1.00024336 ! & %.%%%’ (.’%)* ’ # + ( %.’# #(% ) # = 0.004805161651 Concentration of Unknown NaOH C = mol/vol = 0.025006084 mol / 0.017726 L = 1.410700891mol/L Uncertainty of [Unknown NaOH] e = x ! ( !" " ) # + ( !$ $ ) #

5 = 1.405083604 ! ( %.%( (% ) # + ( %.%+ #( ) # = 0.00365321737 95% Confidence Interval C.I. = x ± ts/ √࠵? = 1.405083604 ± [ (4.303)( 0.007070488)/ √3 ]] = 1.405083604 ± 0.017565483 95% Confidence Interval Range: 1.387518121 M to 1.422649087 M