Acid-Base Titration PDF

Acid-Base Titration Neutralization Reaction A neutralization reaction is a reaction between an acid and a base ? Neutralization Reaction A neutralization reaction is a reaction between an acid and a base acid + base 🡪 salt + water  Titration A titration i...

Acid-Base Titration Neutralization Reaction A neutralization reaction is a reaction between an acid and a base ? Neutralization Reaction A neutralization reaction is a reaction between an acid and a base acid + base 🡪 salt + water  Titration A titration is a common method of quantitative chemical analysis It is used to determine the concentration of a substance in a solution  Table 1 - Titration Terminology Term Definition Device used for dispensing specific Burette amounts of a chemical solution Standard A solution of known concentration Solution Titrant The solution in a burette during a titration Equivalence The point in a titration when neutralization is Point complete The point in a titration where there is a sharp Endpoint change in colour of solution Substance that changes colour at the endpoint; Indicator used to indicate when reaction between two chemicals is complete End Point Indicators Table 2 – Indicator Colour Change as the Endpoint of Titration Indicator Acidic Basic Litmus Red Blue Methyl orange Red Yellow Bromothymol Yellow Green blue Phenolphthale Colourless Red in Steps for Titrating 1. A known volume of the sample to be analyzed is transferred into a flask. The concentration of this solution is unknown Steps for Titrating 2. A few drops of indicator are added to the solution of unknown concentration in the flask Steps for Titrating 3. The burette is filled with the known concentration solution (standard solution) Steps for Titrating 3. The burette is filled with the known concentration solution (standard solution) 4. The solution once in the burette is referred to as the titrant Steps for Titrating 3. The burette is filled with the known concentration solution (standard solution) 4. The solution once in the burette is referred to as the titrant 5. An initial burette volume reading is taken Steps for Titrating 6. The titrant is added drop by drop to the sample in the flask Steps for Titrating 7. The titrant is added until the reaction between the two chemicals is judged to be complete/neutralizati on is complete (i.e., you have reached the equivalent point) Steps for Titrating 7. The titrant is added until the reaction between the two chemicals is judged to be complete/neutralization is complete (i.e., you have reached the equivalent point) 8. The indicator in the flask will change colour at this point (endpoint)  Steps for Titrating 9. At the endpoint, no more titrant is added 10. The volume of titrant that has been used (final burette reading) is recorded 11. This information is used to calculate concentration of the solution in the flask Steps for Titrating At least 3 trials are performed during a titration to improve the reliability of the results (i.e., calculation of concentration) Steps for Setting up and Performing a Titration: https://www.youtube.com/watch?v=sFpFCPTDv2w Applications of Titration Used to analyze acids in the environment (i.e., acids that may be present in freshwater sources) Quality control in industrial and commercial operations Scientific research Practice Problem 1 The concentration of hydrochloric acid, HCl(aq), can be analyzed by titration with sodium hydroxide, NaOH(aq), solution. Three 10.0 mL samples of HCl(aq) are titrated with a standardized 0.200 mol/L solution of NaOH(aq). The results for the three trials are shown in Table 3 below. What is the concentration of HCl(aq)? Table 3 – Titration of HCl(aq) with NaOH(aq) Trial 1 2 3 Average Final burette reading 13.85 mL 26.95 mL 39.85 mL Initial burette reading 0.70 mL 13.90 mL 26.90 mL Volume of NaOH(aq) 13.15 mL 13.05 mL 12.95 mL 13.05 mL added Practice Problem 2 Hydrochloric acid, HCl(aq), is labelled as having a concentration of 0.235 mol/L. To check that the concentration on the label is correct, the solution is analyzed by titration. A 10.0 mL standard solution of 0.150 mol/L sodium carbonte, Na2CO3(aq) is used for the titration. The results for the three trials are shown in Table 4 below. What is the concentration of hydrochloric acid? Table 4 – Titration of Na2CO3(aq) with HCl(aq) Trial 1 2 3 Average Final burette reading 13.35 mL 26.05 mL 38.85 mL Initial burette reading 0.55 mL 13.30 mL 26.00 mL Volume of NaOH(aq) 12.80 mL 12.75 mL 12.85 mL 12.80 mL added