Electrode kinetics: The hydrogen overpotential of metals with Cobra4

Item no.: P3061861 Principle If the oxidation and reduction steps of an electrode reaction are rapid (high exchange current densities) then the passage of charge across the electrode-solution interface will barely displace the reaction equilibrium. Such an electrode is said to be non-polarisable in the sense that its potential, for small currents, is stable and

Chromatographic separation processes: Gas chromatography with Cobra4

Item no.: P3031760 Principle Chromatographic procedures allow a separation of substance mixtures with the aid of a stationary separation phase and a mobile phase. In gas chromatography the mobile phase is a gas. The mobile phase, to which the mixture to be separated is added, transports the substance mixture through the separation column at a

Dissociation equilibrium with Cobra4

Item no.: P3030960 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. Tasks Measure the alteration of the pH value during a titration of approximately 0.1

Determination of the Michaelis constant with Cobra4

Item no.: P4120360 Principle The enzymatic hydrolysis of urea in aqueous solution liberates carbon dixide and ammonia. The ions of these compounds increase the conductivity of the solution. Conductivity measurements can so be made to determine the rate of hydrolysis of urea by the enzyme urease at various substrate concentrations. Tasks The Michaelis constant can

Electronystagmography with Cobra4

Item no.: P4070760 Principle Electronystagmography (ENG) is an electrophysiological diagnostic procedure for measuring the movement of the eyes. Several electrodes measure the potential differences that are caused by the eye movements. When looking at a moving, regular, repetitive pattern (e.g. the wagons of a passing train, stripes on a rotating drum), the eyes usually try

We investigate our physical fitness – the heart under stress with Cobra4

Item no.: P1522160 Principle An electrocardiogram (ECG) can record the sum of the electrical activities of all of the heart muscle fibres. Under stress, cardiac activity increases in order to maintain the stability of the cardiovascular system. The heart contraction cannot be controlled at will. This experiment enables you to study how physical stress affects

Photosynthesis with Cobra4

Item no.: P4110260 Principle Photosynthesis leads to the production of oxygen, which in turn causes the pressure to rise. In this experiment the photosynthesis rate of a plant is determined by measuring the oxygen pressure increase, in white and green light as well as in the dark. Tasks To compare the increase in oxygen pressure

Measuring reading skills with Cobra4

Item no.: P1522260 Principle With this experiment, you can determine your own personal reading speed. One’s reading speed can be trained and is an important prerequisite for the proper handling of all kinds of texts. You can precisely study the movement of your eyes during the measurement. Tasks Explore your reading behaviour reading easy and