Experiment examples – physics
Cobra4
Experiment examples – chemistry
wireless Ohm’s law
P1330360
Manual pH titration
P1510260
The relation between the electrical voltage and the resulting current is measured with various test resistors. The quotient of the voltage and current is a constant value that characterises the component. The various measurement curves can be displayed in a particularly clear manner in a graph.
pH titrations are among the most frequent tests of acids and alkaline solutions. If a pH electrode is used to determine the end point, it also is possible to test highly coloured solutions and to observe the changes of the pH value during the entire reaction. The Cobra4 interface records and evaluates the measurement data in a particularly comfortable way. If a burette is used as the volumeter, the titration solution can be added particularly easily.
Excerpt from the equipment list Excerpt from the equipment list
Quantity
Name
Ref. no.
Quantity
Name
Ref. no.
1
Cobra4 Wireless Manager
12600.00
1
Cobra4 Wireless Manager
12600.00
1
Cobra4 Wireless-Link
12601.00
1
Cobra4 Wireless-Link
12601.00
1
Cobra4 Sensor-Unit “pH and 2 x temperature NiCr-Ni”
12630.00
1
Cobra4 Sensor-Unit “Electricity”
12644.00
1
Holder for Cobra4 with a stand
12680.00
1
Software “measure” for Cobra4
14550.61
1
Software “measure” for Cobra4
14550.61
Also required: cables, other components, small parts, and a PC
Generation of alternating voltage, rectification, and smoothing
Also required: small parts, support materials, chemicals, and a PC
P1331360
Oscillating reaction
P1510460
An alternating voltage is induced in a coil in the (alternating) field of a magnet that moves periodically. The characteristic of a diode, i.e. the fact that it lets the electrical current pass only in one direction is used to rectify the induced alternating voltage. A capacitor that is connected in parallel to the consumer (resistor) smoothes the rectified alternating voltage.
Observing oscillating reactions, e.g. the Briggs-Rauscher reaction, is highly fascinating. If a platinum electrode and an Ag/AgCl reference electrode are immersed into the reaction mixture, the electrochemical potential that changes along with the colour can be observed potentiometrically.
Excerpt from the equipment list Excerpt from the equipment list
Name
Ref. no.
Quantity
Name
Ref. no.
1
Cobra4 Wireless Manager
12600.00
1
Cobra4 Wireless Manager
12600.00
1
Cobra4 Wireless-Link
12601.00
1
Cobra4 Wireless-Link
12601.00
1
Cobra4 Sensor-Unit “pH and 2 x temperature NiCr-Ni”
12630.00
1
Cobra4 Sensor-Unit “Electricity”
12644.00
1
Holder for Cobra4 with a stand
12680.00
1
Software “measure” for Cobra4
14550.61
1
Software “measure” for Cobra4
14550.61
Also required: cables, other components, small parts and a PC
Specific heat capacity of water
Also required: small parts, support materials, chemicals, and a PC
P1349160
Temperature-dependence of the conductivity
P1510160
The electrical conductivity depends not only on the type and concentration of the electrolytes, but also on other parameters. If the temperature increases, one can usually also observe an increase in conductivity. At some point, however, a certain limit is reached, as of which the conductivity decreases even if the temperature increases further. For aqueous solutions, this value is approximately 90°C. The temperature-dependence of the conductivity can be studied with this experiment.
Cold water is filled into a calorimeter and heated with a heating coil. The relation between the heating power and the temperature rise is displayed and the specific heat capacity of water is calculated.
Excerpt from the equipment list Quantity
Name
Ref. no.
Excerpt from the equipment list
1
Cobra4 Wireless Manager
12600.00
Quantity
Name
Ref no.
2
Cobra4 Wireless-Link
12601.00
1
Cobra4 Wireless Manager
12600.00
1
Cobra4 Sensor-Unit “Electricity”
12644.00
1
Cobra4 Wireless-Link
12601.00
1
Cobra4 Sensor-Unit “Temperature, semiconductor –20...+110°C”
12640.00
1
Cobra4 Sensor-Unit “Conductivity + (Pt 1000)”
12632.00
1
Student calorimeter
04404.88
1
Holder for Cobra4 with a stand
12680.00
1
Software “measure” for Cobra4
14550.61
1
Software “measure” for Cobra4
14550.61
Also required: small parts, support materials, chemicals, and a PC
Also required: power supply unit, calorimeter, cables, small parts, and a PC
excellence in science
Quantity
excellence in science
12 13