Acid dissociation constant

Discussion and Scientific Explanation The initial goal of this experiment was to investigate the properties of an unknown acid or base. These properties include pH, concentration, and how the solution behaves once titrated. In order to accomplish these goals, the initial pH of the unknown compound needed to be found through the use of pH strips and/or a PASCO probe. It was also necessary to titrate the unknown compound to find the equivalence point, which would allow the calculation of the initial

From the pH at the equivalence point, the dissociation constant of the acidic or basic group can be determined (see chemical equilibrium). If a compound contains several different acidic or basic groups, the titration curve will show several sigmoid-shaped curves like steps and the dissociation constant of each group can be obtained from the pH at its corresponding equivalence point. I have now explained

Objective In this experiment, the pKa*, dissociation constant, of 2-naphthol in an excited state was determined by measuring its fluorescence spectrum. Procedure In this experiment, a solution of 2-naphthol in HCl and a solution of 2-naphthol in NaOH are analyzed by measuring their UV-visible (obtained from the Cary 50 spectrophotometer) and fluorescence spectrum (obtained from the PTI fluorometer). For detailed procedure, refer to the lab manual (J. F. Wójcik and T. S. Ahmadi, Experimental Physical

previous section. Results Discussion and Conclusion Table 1 There is minimal change in the pH of the buffer with a high of 6.78 and a low of 6.47. The equivalence point is approximately 6.64. This shows that as the quantity of the buffering agent's acid (HA) and conjugate base (A-) changes, the buffering capacity of the solution decreases. As a consequence, a buffer agent can only be utilized up to a given point in which case it does not resist pH changes and seizes to be a buffer solution. Table

Objective In this experiment, the pKa, dissociation constant, of 2-naphthol was determined by measuring the UV-visible absorption spectra of solution of the acid at different pH values. Procedure In this experiment, solutions of 2-naphthol will be prepared in buffer solutions with pH values near the expected pKa (refer to Table 7.1 in the lab Manual) at 25 °C and the UV-visble spectra of each solution will be measured using a Cary 50 spectrometer. For detailed procedure, refer to the lab manual

Extended Response Task- Acid and Bases Introduction: A buffer solution is a solution (consisting of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid), which minimises changes in pH when small quantities of acids or bases are added to it. In a way, it is used to consistently moderate the pH of a solution, and is measured using the Acid Dissociation Constant. General Formula: HA⇋H^++A^- NaA⇋N^++A^- Where HA is a weak acid, N+ is a salt, and A- is a weak base.

Capacity: in regards to the two different concentrations of Acetic acid/acetate buffers (0.060M & 0.030M) : HCl NaOH Solution A | 9.0 mL | 9.0 mL | Solution C | 4.0 mL | 6.0 mL | Since the M of NH3/NH4 buffer is twice as much as the acetic acid/acetate buffer, we expect the buffer capacity for Solution A to be

6-dichlorophenolindophenol) will react with Vitamin C by redox titration (turning the solution from pink to colourless)(en.wikipedia.org). Vitamin C and DCPIP react in a 1:1 mole ratio and hence if a known amount of DCPIP is used; it is easy to find the mass of ascorbic acid sample as it is a direct measure (saps.org.uk)(microbiologyinfo.com). HC12H6Cl2O2N + 2H+ + 2e- HCl12H8Cl2O2N Red C6H8O6

concentration of NaOH was used to identify the unknown acids, this value is shown is experiment 16.1. This mean standardized concentration was 0.0784 M. By titrating a known amount and concentration of this standardized base to the unknown acid, a titration curve and its derivative could be plotted in order to find the molar mass and acid dissociation constant. The first unknown acid titrated, BGYW, was identified to be Maleic acid, C4H4O4. The identity of the acid was found by taking both the molar mass and

Hydrochloric Acid and Phosphoric Acid in an Unknown HCl – H3PO4 Mixture through Use of Potentiometric Titrations Andrea Byassee 8000 Utopia Parkway Department of Chemistry St. John’s University Jamaica, NY 11439 andrea.byassee12@stjohns.edu Report Prepared for: Quantitative Chemical Analysis Professor Neil Jespersen Due Date: October 16, 2014 Submitted Date: October 20, 2014 ABSTRACT The purpose of this experiment was to determine if soft drinks manufactured by Coca-Cola use phosphoric acid in their