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Absorption spectra and pKa values of p-methoxyphenol

Product No: P3070401

Principle

For weak acids HA, the position of the K_a and pK_a values that characterize the dissociation equilibrium in the ground state can be determined from photometric measurements in solutions having different pH values. Further to this, the pK_a* value for the excited state is accessible from the spectrophotometric data.

Tasks

Record near UV absorption spectra of p-methoxyphenol in dilute HCl, NaOH and 5 different borate buffer solutions of known pH.
Calculate the pK_a and pK_a* values for the system.

What you can learn about

Ground and excitation states of molecules
Electron excitation spectroscopy (UV-visible spectrometry)
Spectroscopical energy and adsorption measurement
Jablonski diagram and Förster cycle
pK_aand pK_a* values
Henderson-Hasselbalch equation
Van't Hoff's reaction isotherms
Gibbs-Helmholtz equation
Lambert-Beer's Law
Photometry

Materiallist (Excerpt)	Product	Amount
Spectrophotometer 190-1100 nm	35655-93	1
Set of Precision Balance Sartorius CPA 623S and measure software, 230 V	49224-88	1
pH/Potenial meter, Cobra4-Mobile Link, hand-held	12739-00	1
Cells f.spectrophotom., quartz, 2	35665-02	1
pH-electrode, plastic body, gel, BNC	46265-15	1
Retort stand, h 750 mm	37694-00	1
Burette, lateral stopcock, Schellbach, 50 ml, graduations 0, ml	36513-01	1
Burette clamp, roller mount.,2pl.	37720-00	1
Thermometer -10...+50 C	38034-00	1
Caustic soda sol.,0.1M 1000 ml	48328-70	2
Hydrochloric acid,0.1M 1000 ml	48452-70	1
Hydroquinone monomethyl ether 5 g	31055-02	1
Water, distilled 5 l	31246-81	1
Protection sleeve for electrode with a diameter of 12 mm	37651-15	1
Volumetric flask 1000ml, IGJ24/29	36552-00	1
Buffer solution, pH 10.01,1000 ml	46272-12	1
Buffer solution, pH 7.01, 1000 ml	46271-12	1
Boric acid, powder 250 g	30044-25	1
Potassium chloride 250 g	30098-25	1
Pipettor	36592-00	1
Volumetric flask 250 ml, IGJ14/23	36550-00	1
Pasteur pipettes, 250 pcs	36590-00	1
Weighing dishes, square shape, 84 x 84 x 24 mm, 25 pcs.	45019-25	1
Volumetric flask 100 ml, IGJ12/21	36548-00	5
Volumetric flask 50 ml, IGJ12/21	36547-00	7
Rubber caps, 10 pcs	39275-03	1
Microspoon, steel	33393-00	1
Volumetric pipette, 5 ml	36577-00	1
Funnel, glass, top dia. 55 mm	34457-00	2
Wash bottle, plastic, 500 ml	33931-00	1
Laboratory Experiments Physics, Chemistry, Biology andApplied Sciences, CD-ROM, incl. operating manuals	16502-42	1