a. 25 mL of 0.1 M lactic acid (HC3H5O3, pka= 3.86) was transferred o a conical flask and titrated with 0.15 M NaOH solut

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A 25 Ml Of 0 1 M Lactic Acid Hc3h5o3 Pka 3 86 Was Transferred O A Conical Flask And Titrated With 0 15 M Naoh Solut 1 (51.48 KiB) Viewed 50 times

a. 25 mL of 0.1 M lactic acid (HC3H5O3, pka= 3.86) was transferred o a conical flask and titrated with 0.15 M NaOH solution i. Calculate the pH of the solution after adding 0 mL of NaOH. Show all workings. (6 marks) ii. Indicate how many mL of 0.15 M NaOH must be added to the lactic acid solution to reach the equivalence. Show all workings. (2 marks) ill. From the list below, select the appropriate indicator for this titration. Explain your answer (2 marks) Base Color orange purple pH range 3.1-4.4 pka 3.7 5.2-6.8 6.1 Indicator Acid Color Methyl orange red Bromocresol Yellow purple Bromothymol yellow blue phenolphthalein colorless blue 6.0-7.6 7.1 red 8.3-10.0 8.9 b. Quantitative determination of the ibuprofen content of a tablet gave the following results: Measurement 1: 300 mg Measurement 2: 295 mg Measurement 3: 301 mg Measurement 4: 305 mg Measurement 5: 299 mg Calculate the mean value of ibuprofen (in moles) present in the tablet. The molecular mass of ibuprofen is 206.28 g/mol. [2 marks] Calculate the standard deviation and the confidence interval for the true value at 95% confidence interval. [4 marks] i. ii.