Acid-base titration represents an analytical procedure for determining concentrations of corresponding compounds. The use of pH measuring electrodes also offers the possibility of creating measurement curves.

In this experiment, students record a measurement curve for the titration of a strong acid (hydrochloric acid) with a strong base (sodium hydroxide solution). In doing so, they will then identify the characteristic features of such a titration curve and determine the equivalence point. In the process, the students learn, among other things, that for titrations with strong bases and acids, equivalence point = neutral point. At the equivalence point, the base and the acid are present in equal proportions. The following applies: n(acid) = n(base) This statement can be used to calculate the concentration of the acid.

Benefits

• The experiment is part of a complete solution with numerous experiments from the field of titration and ion detection, and can be used as part of a teaching unit
• In addition to the graphical representation of the measurement data on the measuring instrument, all data can also be transferred to a computer for evaluation
• Experimental literature available for students and teachers: minimum preparation time
• Risk assessment available for students and teachers
• Easy teaching and efficient learning when using the available interactive experimental literature

Perfect for student experiments.

Function and Applications
Cobra SMARTsense is the ideal solution for inexpensive digitalization of science teaching. The sensors connect wirelessly (Bluetooth) or wired (USB) directly to the student’s digital end device (smartphone, tablet or desktop PC). Using the free and award-winning measureAPP measurement software for iOS, Android and Windows, measured values can be easily recorded and graphically displayed. If more evaluations are needed, the measureLAB measurement software for Windows and macOS can be used.

With the sensor, single drops can be counted and directly converted into a volume. If you connect a pH electrode, a titration can be carried out easily and precisely.

Benefits

• Simplicity – Get started right away with the Bluetooth-enabled end device and the free measureAPP
• Completeness – Over 40 sensors with more than 70 measured quantities for all subjects
• Endurance – Intelligent and efficient power management for up to 50 hours on one battery charge
• Variety – The free measureAPP provides perfect support and runs on all mobile platforms and end devices. For professionals, measureLAB is available.
• Performance – Up to 32,000 measured values per second guarantee precision and recordings with up to 17 measuring channels simulaneously are possible.
• Connectivity – Fast connection of sensors and data exchange via Bluetooth – for many sensors additionally possible via USB.

Equipment and Technical Data

• Dropcounter:
  • Range: 0 … ∞
  • Resolution:30 Imp/s
• pH:
  • Range: 0 … 14
  • Resolution: 0.01
• Samplerate: 50 Hz

The PH-Elektrode is sold seperately.

The sensor contains a USB-C rechargeable lithium polymer battery.

Different salts can be caused to react with each other while at the same time an exchange of cations or anions takes place.If during this process a salt precipitates out in the form  of an insoluble component, this can be taken as a test reaction.

Tasks

Prepare several salt solutions and study the processes taking place when the solutions are mixed.

Benefits

• Easy teaching and efficient learning by using interactive experimentation IMPACT-Software
• Experiment is part of a complete solution set with experiments for the topic acids, alkalis and salts matched with international curriculum: all topics are covered

Nitrogen, which is present in many substances, can frequently be transformed into ammonia. Ammonia, and thus nitrogen, can be recognised by its characteristic odour. Two test tubes are filled with sodium hydroxide flakes and either ammonium chloride or gelatine powder. The test tubes are heated over a burner and an odour test is performed.

Hydrogen is a colourless, explosive gas. Due to its explosiveness, hydrogen can be identified by holding the test tube over the flame of a Bunsen burner as oxyhydrogen gas.

For the detection of oxygen there are different methods. A simple and very quick detection of oxygen, which is produced in a chemical reaction, is called glowing splint.  The resurgence of the chip (glowing splint) identifies the production of oxygen.

Mixtures can be separated by different physical separation processes into its components. An important separation method is chromatography. In this experiment dyes are separated by chromatography into individual components. This experiment shows that monochrome appearing dyes can be separated in several different coloured substances.  A further segregation of the prepared leaf pigment and a felt-tipped pen ink are shown in this experiment.

Function and Applications
DNA analysis has never been so simple and clear. Our experimental set contains all the necessary equipment needed for experiments in genetics, including the sensational blueGel gel electrophoresis system and the practical 3-in-1 agarose tablets (agarose, TBE-salt and a fluorescent dye). In addition, the set contains a washable pipetting practice card, which saves time and material when training with the pipette. The 3-in-1 agarose tablets, together with the blueGel system, allows visualization of DNA separation while it is being performed! Latest LED technology makes UV light superfluous. The enclosed foldable darkroom allows filming and photographing with your own smart phone. Gel electrophoresis finally without high voltage; the 48V power supply unit for electrophoresis is included. The 3-in-1 agarose tablets contain agarose, TBE and a harmless fluorescent dye that makes DNA and RNA glow – just add water, boil it up, and you are done.
Benefits

• All necessary equipment for gel electrophoresis in one set, including the power supply for electrophoresis.
• Included are the blueGel gel electrophoresis system and the 3-in-1 agarose tablets, which together enable live observation through built-in LED.
• No harmful chemicals required.
• Microliter pipette (2 µl – 20 µl), matching tips and a pipetting practice card are also included.
• Minimum preparation time.

Equipment and Technical Data

• The equipment set consists of all components necessary for the experiments; only the TBE electrophoresis buffer must be purchased separately.
• Stable, stackable storage boxes with unit-shaped foam insert
• Four kits available (to purchase separately): plasmid DNA, Lambda DNA, DNA fingerprinting, paternity test

Chromatographic separation processes are very important for analytical chemistry. Their relatively simple technique and the possibility to separate even the smallest portions of mixtures explain the rapid development of these processes. There are numerous variations of this method.

As a result, the optimum chromatographic separation method can be found for nearly every separation task. The method that is described here can be used to demonstrate the fundamental principles and possibilities of this method with relatively simple means.

Benefits

• Didactic introduction to a basic separation process

Tasks

Separate a dye mixture by thin-layer chromatography.

Learning objectives

• Thin-layer chromatography
• Separation procedure
• Adsorbent material
• Stationary phase
• Mobile phase
• Capillary action

In this investigation, a uniformly green raw extract of fresh leaves is first separated into different fractions by means of column chromatography. To do so, the extract is added to a column filled with starch and drawn through the column under slightly reduced pressure (to increase the flow rate of the mobile phase) with ligroin as the eluent. A separation occurs in a clearly recognisable, broad, yellow area and in a narrow, green band. This means that the xanthophylls (yellow) are separated from the chlorophylls (green). If the vacuum is reduced during the separation, the separation is much better, but then separation also takes considerably longer. Each of the separation fractions can be collected individually and characterised by recording their absorption spectra, if necessary, or examined for fluorescence by radiation with UV light.

Benefits

• Optimised for demonstration experiments: Transformation from horizontal into vertical direction
• Practical water jet pump for easy generation of the required negative pressure
• Didactic introduction to a basic separation process

Tasks

Investigate different leaf pigments using column chromatography.

Learning objectives

• Chlorophyll
• Column chromatography
• Leaf pigments
• Xanthophyll