Product details

Dissociation equilibrium with Cobra4

Dissociation equilibrium with Cobra4

Item no.: P3030960

Experiment Type: Teacher Experiment, Laboratory Experiment

Difficulty Expenditure of Time print
  • Description
  • Scope of Supply
  • Accessories
  • Downloads and Documents

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

  1. 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 Cobra4 system.
  2. From the neutralisation curves read the pKa values of the acids and compare them.

What you can learn about

  • 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.

 

Device Name Item no. Qty
curricuLAB measureLAB 14580-61 1,00
Monochloroacetic acid 100 g 30060-10 1,00
USB charger for Cobra4 Mobile-Link 2 and Wireless/USB-Link 07932-99 2,00
Magnetic stirring bar 15 mm, cylindrical 46299-01 1,00
Right angle boss-head clamp 37697-00 3,00
Burette, lateral stopcock, Schellbach, 25 ml 36506-01 1,00
Water, distilled 5 l 31246-81 1,00
Holder for sensors with support rod 12680-00 2,00
Beaker, 50 ml, high-form 46025-00 2,00
Pasteur pipettes, 250 pcs 36590-00 1,00
Wash bottle, plastic, 500 ml 33931-00 1,00
Lactic acid 100 30264-10 1,00
Cobra4 Wireless/USB-Link incl. USB cable 12601-10 2,00
Caustic soda sol.,0.1M 1000 48328-70 1,00
Burette clamp, roller mount., 2 pl. 37720-00 1,00
Volumetric flask 100 ml, IGJ12/21 36548-00 6,00
Acetic acid 99...100%, pure 1 31301-70 1,00
Immersion probe NiCr-Ni, teflon, 300 °C 13615-05 1,00
Beaker, 250 ml, high-form 46027-00 1,00
Pipettor 36592-00 1,00
Magnetic stirrer without heating, 3 ltr., 230 V 35761-99 1,00
Buffer solution, pH 4.62 1000 30280-70 1,00
Cobra4 Sensor-Unit Chemistry 12630-00 1,00
Rubber stopper,d=18/14mm, 1 hole 39254-01 1,00
Volumetric pipette, 5 ml 36577-00 6,00
Propionic acid, 500 31753-50 1,00
N-butyric acid 100 30047-10 1,00
pH-electrode, plastic body, gel, BNC 46265-15 1,00
Retort stand, h = 750 mm 37694-00 1,00
Beaker, tall form, 150 ml 36003-00 1,00
Buffer solution, pH 9 1000 30289-70 1,00
Cobra4 Sensor-Unit Drop Counter 12636-00 1,00
Rubber caps, 10 pcs 39275-03 1,00
Pipette dish 36589-00 1,00
Microspoon, steel 33393-00 1,00
Document     Filesize
p3030960e.pdf Experiment guide, English 541.24 KB

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