Specifične toplotne kapacitete raztopin elektrolitov

Smrečnik, Saša (avtor), Cerar, Janez (mentor)

V tem delu sem z uporabo diferenčnega dinamičnega kalorimetra poskusila izmeriti temperaturno odvisnost specifičnih toplotnih kapacitet 2 M vodnih raztopin mešanic soli NaBr in KF, v katerih sem spreminjala razmerje med obema elektrolitoma, pri tem pa je skupna koncentracija soli pri 25 °C vedno ostala enaka 2 mol/dm3. Kot referenčno tekočino sem pri teh meritvah uporabljala zelo čisto vodo (tip 1), pripravljeno z ionskim izmenjevalcem. Meritve v območju med 5 °C in 60 °C sem opravila z Nano DSC diferenčnim dinamičnim kalorimetrom proizvajalca TA Instruments. Zelo pomemben del te naloge je bil določiti napako, ki spremlja določevanje teh specifičnih toplotnih kapacitet ter po možnosti tudi odkriti, kako to napako v največji možni meri zmanjšati. Termogrami, pridobljeni pri teh poskusih, so bili v območju višjih temperatur obremenjeni s precejšnjim nihanjem signala, kar sem opazila šele potem, ko sem vse termograme posnela. Vzrok temu nihanju, ki ga pri normalnem delovanju instrumenta ni, je najverjetneje vdor zraka iz okolice v evakuiran prostor, ki obdaja merilni celici. Če bi želela zadano nalogo v okviru tega diplomskega dela v celoti izpolniti, bi bilo potrebno najprej ponovno vzpostaviti vakuum okoli celic ter nato poskuse v celoti ponoviti.

• Jezik: Slovenski jezik
• Ključne besede: Nano DSC, diferenčna dinamična kalorimetrija, specifična toplotna kapaciteta, raztopine elektrolitov
• Vrsta gradiva: Diplomsko delo/naloga
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Leto izida: 2024
• PID: 20.500.12556/RUL-161371
• Datum objave v RUL: 10.09.2024

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Specific heat capacities of electrolyte solutions

Izvleček

In this work, using a differential scanning calorimeter, I tried to measure the temperature dependence of the specific heat capacities of 2 M aqueous solutions of mixed NaBr and KF salts, in which I changed the ratio between the two electrolytes, while the total salt concentration always remained equal to 2 mol/dm3. As a reference liquid for these measurements, I used very pure water (type 1), prepared with an ion exchanger. I made measurements in the range between 5 °C and 60 °C with a Nano DSC differential scanning calorimeter from TA Instruments. A very important part of this task was to determine the error that accompanies the determination of these specific heat capacities and, if possible, to discover how to reduce this error as much as possible. The thermograms obtained during these experiments were burdened with considerable signal fluctuation in the higher temperature range, which I noticed only after I recorded all the thermograms. The cause of this fluctuation, which is not present during normal operation of the instrument, is most likely the intrusion of air from the surroundings into the evacuated space surrounding the measuring cell. If I wanted to fully fulfill the assigned task within the framework of this diploma work, it would first be necessary to re-establish the vacuum around the cells and then repeat the experiments in their entirety.

• Ključne besede: Nano DSC, differential scanning calorimetry, specific heat capacity, electrolite solutions