Question

Styles Styles Pane Name Station # Date CHM 112 Acid - Base Titration using pH Sensor Report Sheet and Data Analysis DATA ANALYSIS Report your answers to three (3) significant figures. 1. Calculate the molar amounts of NaOH used in the reaction with the HCl solution and with the HC H3O2 solution. (record your answer in Table 3) NaOH and HCI NaOH and Acetic Acid 2. Calculate the molar concentration (molarity) of the HCl solution and the HCHO. solution (record your answer in Table 3) NaOH and HCI NaOH and Acetic Acid 3. Compare the actual molar concentrations of your two acid solutions with your calculated molarities. Were the calculated molarities of your acid solutions within a reasonable range (about 5%) of the actual values? If not, suggest reasons for the inaccuracy. United States) Focus E

Answer 1

the chemical equations for the reactions are

NaOH + HCl NaCl + H₂O

CH₃COOH+ NaOH CH₃COONa + H₂O

for ideal reaction both the cases one mol of each of the acids and base are used. so the table 1 will be

NaOH and HCl	acetic acid and NaOH
1	1

M1V1= M2V2

the strong acid strong base titration the equivalence point will be at neutral pH 7

so taking the equation and putting the values of V1 =20mL M1=1mol V2 =19.65 the molarity of HCl will be =20/19.50= 1.02molL^-1

in case of weak acid strong base titration the equivalence point will be slightly basic and the voulume acetic acid used is around 9. 6

therefore substituting in the equation we get the concentration of acetic acid as = 10/9.6 =1.04 mol

so the table 2 will be

HCl and NaOH	acetic acid and NaOH
1.02	1.04

the deviation is because the exact neutralisation point for weak acid and strong base is not exactly at neutral pH of 7 but it is slightly basic. if it was at exactly at 7 tyhen the molarity of acetic acid will be 10/9.05 =1.05 mol l-1