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Control of the trace element content in tap water is particularly important for large industrial regions. The estimation of Cd, Pb, Cu, As, Ni, Zn, Mn, Hg, Se and Co concentration in the tap water of Kryvyi Rih city (Karachuny Reservoir) was accomplished using electrochemical methods, the most popular methods for determining the content of trace elements in natural objects and tap water. A simple and rapid method to determine trace elements in the tap water (Kryvyi Rih city) by inversion-voltammetry has been used. The concentration of trace elements was measured by voltammetricanalyzer AVA-2 device that implements the method of inversion voltammetry on a solid rotating electrode made of carbon material. The monitoring of the trace element content in the water of the Karachuny reservoir was carried out on a monthly basis between September 2018 and August 2019. The article presents the obtained voltamperograms of some trace elements, describes content of the trace element in tap water during the year (12 data for each trace element) and analyzes the compliance of drinking water in the city of Kryvyi Rih to the standards and normative indicators of drinking water quality.

Electrochemical devices based on nickel hydroxide electrodes are used in different areas. The main ones are chemical current sources, variable transparency “smart” windows, devices for carrying out electrocatalytic reactions, sensors for determining various substances. In this regard, methods of nickel hydroxide synthesis are of great interest, especially those that allow forming nickel hydroxide directly on the surface of electrodes. One of these methods is electrochemical deposition with cathodic current polarization. The available information on nickel hydroxide synthesis from nickel solutions was considered. It was shown that the available data mainly covered information on dilute solutions from 0.01 to 0.25 mol/L Ni(NO3)2. In addition, no comparison was found in the literature for the efficiency of the cathodic formation of Ni(OH)2 at different concentrations of nickel nitrate. To eliminate the lack of information, the dependence of the current efficiency on the concentration of nickel nitrate in the electrodeposition solution was determined at a constant cathode current density of 0.625 mA/cm2. The resulting dependence decreased nonlinearly with increasing concentration. The nickel hydroxide deposit formed in this case had an X-ray amorphous structure, and it depended little on the Ni(NO3)2 concentration. In addition, the current efficiency reached zero at concentrations of 1.5 mol/L Ni(NO3)2 and higher. However, with polyvinyl alcohol in the solution and at Ni(NO3)2 concentrations of 1.5 and 2 mol/L, electrochemically and electrochromically active Ni(OH)2 films were deposited. The current efficiency calculated indirectly for 1.5 and 2 mol/L Ni(NO3)2 solutions was 3.2 and 2.3 %, respectively. Thus, it was concluded that polyvinyl alcohol affected the mechanism of nickel hydroxide electrodeposition from aqueous solutions of nickel nitrate.

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A training kit has been created to study the topic of “Oxygen-containing organic compounds” using augmented reality. We chose the Blippar platform to work, it is quite simple and relatively free. The kit contains markers we have developed, on which, with the camera from the Blippar application, students will be able to observe thematic experiments and molecules of individual substances with the help of augmented reality. There was also a study on the effectiveness of our developments to implement augmented reality in the course of chemistry. The study results showed an increase in pupils’ motivation to study chemistry and their level of interest, facilitating the perception of the theoretical foundations of organic chemistry related to the spatial structure of molecules. Also, the use of augmented reality technologies creates the conditions for improving the level of digital and technological competencies of students, provides support for high quality teaching of chemistry in distance learning.