Technical data

Dissociation equilibrium with Cobra SMARTsense

Article no: P3030967

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Principle

Carboxylic acids are potential electrolytes which exist in a weakly dissociated condition in aqueous solutions. The location of the dissociation equilibrium is quantitatively described by the Ka or pKa value which can be determined with potentiometric measurements.

Benefits

Simplified implementation: all pre-settings already prepared
Drop counter optimizes the experimental procedure

Tasks

Measure the alteration of the pH value during a titration of approximately 0.1 molar aqueous solutions of formic acid, acetic acid, monochloroacetic acid, propionic acid, butyric acid and lactic acid with a 0.1 molar sodium hydroxide solution at constant temperature using Cobra SMARTsense-system.
From the neutralisation curves read the pKa values of the acids and compare them.

Learning objectives

True and potential electrolytes
Strong and weak acids
Law of mass action
Henderson-Hasselbalch equation
Dissociation constant and pKa value
Substituent effects
Potentiometry

Necessary accessories

Precision balance 620g/0.001g

Software included. Computer not provided.

Scope of delivery

Cobra SMARTsense Dropcounter - Sensor for measuring drops and pH during titration 0 ... ∞ / 0 ... 14 (Bluetooth + USB)	12923-00	1
measureLAB, multi-user license	14580-61	1
Immersion probe NiCr-Ni, teflon, 300 °C	13615-05	1
Magnetic stirrer without heating, 3 ltr., 230 V	35761-99	1
Magnetic stirring bar 15 mm, cylindrical	46299-01	1
Beakers, Boro, high form, various sizes	46025-00	2
Beakers, Boro, high form, various sizes	46032-00	1
Beakers, Boro, high form, various sizes	46027-00	1
Volumetric flasks, Boro, various sizes	36548-00	6
Bulb pipettes, various sizes	36577-00	6
Pipettor	36592-00	1
Pipette dish	36589-00	1
Pasteur pipettes, 250 pcs	36590-00	1
Rubber caps, 10 pcs	39275-03	1
Microspoon, steel	33393-00	1
Wash bottle, plastic, 500 ml	33931-00	1
Buffer solution, various pH values	30280-70	1
Buffer solution, various pH values	30289-70	1
Acetic acid 99...100%, pure 1 l	31301-70	1
Monochloroacetic acid 100 g	30060-10	1
Propionic acid, 500 ml	31753-50	1
N-butyric acid 100 ml	30047-10	1
Lactic acid 100 ml	30264-10	1
Caustic soda sol.,0.1M 1000 ml	48328-70	1
pH-electrode for Cobra SMARTsense pH, BNC	12920-10	1
Stand rods, stainless steel, various sizes	02030-15	2
Right angle boss-head clamp	37697-00	3
Retort stand, h = 750 mm	37694-00	1
USB charger for Cobra SMARTsense and Cobra4	07938-99	2
Burette clamp, roller mount.,1pl.	37720-01	1
Burette, lateral stopcock, Schellbach, 50 ml	MAU-24022024	1
Cobra SMARTsense Thermocouple - Sensor for measuring temperature -200 ... +1200 °C (Bluetooth + USB)	12938-01	1
Holder for Cobra SMARTsense	12960-00	1