by Umit B. Demirci and Laurent Bernaud
Original Research
Because our undergraduate chemistry students hear about metal organic frameworks (MOF) within the plan of the teaching units dedicated to inorganic chemistry and coordination chemistry, we initiated in 2017-2018 an inorganic chemistry laboratory experiment aimed at third-year undergraduate students (7 sessions of 4 h each). The laboratory focuses on the synthesis and analysis of the ZIF-8, a well-documented and easy-to-synthesize MOF. Students are introduced to coordination chemistry, MOFs, solvothermal synthesis, analysis techniques (scanning electron microscopy, X-ray diffraction, Fourier transform infra-red spectroscopy, thermogravimetric analysis), and 3D visualization of the structural models of crystalline solids. Prior to any discussion with the instructor, the students are strongly encouraged to analyze their collected data based on the open literature, and it is expected that they will develop their autonomy. The students gain experimental independency. After the laboratory experiment, the students prepare a poster (2 dedicated sessions, of 4 h each), and present it during an oral examination (10th session) in front of a jury of four instructors. In this way, they are assessed. We believe that this inorganic chemistry laboratory experiment could be adopted by other laboratories as it is, or in an adapted form. Some suggestions to adapt it are made.
World Journal of Chemical Education. 2022, 10(3), 114-123. DOI: 10.12691/wjce-10-3-5
Pub. Date: September 05, 2022
1688 Views3 Downloads
by Sujata Sengupta, Sharda Mahilkar Sonkar, Shivani Singh, Ankita Duggal and Mamta Siwach
Original Research
Chemistry students in their college laboratory routinely employ qualitative reactivity patterns to identify functional groups of unknown organic compounds. Qualitative organic analysis is therefore very useful for determining the overall structure. Most of the common functional groups can be easily detected by simple color tests that are rapid, simple and routinely performed by the students. However, the detection of aromatic hydrocarbons and aryl halides is still a challenge as there are not many color tests available. The present work highlights the detection of aromatic hydrocarbons and aryl halides by simple modification of their reaction with chloroform. The method is simple, using chemicals that are easily available in the undergraduate laboratory and follows the principles of green chemistry.
World Journal of Chemical Education. 2022, 10(3), 110-113. DOI: 10.12691/wjce-10-3-4
Pub. Date: August 03, 2022
1701 Views1 Downloads
by R. Sanjeev, R. Ravi, D. A. Padmavathi and V. Jagannadham
Original Research
Extrapolation of a simple straight-line graph is used to calculate the pKaH of two cations (CH2N5+) and (HN6+) (eqn. 1 and 2) of two hypothetical molecules pentazine (CHN5) and hexazine (N6). This is achieved by simply an extrapolation of the locus of the plot of pKaH of protonated pyridine, pyridazines, s-triazine and 1,2,4,5-tetrazine versus the number of nitrogen atoms of the cyclic azines. Even well matched pKaH values for these two species were found from the extrapolation of the locus of the plot of pKaH versus average ionization potential (Iv/eV) of the neutral azines. This article is useful in graduate research classroom to explain the acid-base properties and to determine the pKaH values.
World Journal of Chemical Education. 2022, 10(3), 105-109. DOI: 10.12691/wjce-10-3-3
Pub. Date: August 03, 2022
1727 Views2 Downloads
by Kriti Singh, S. K. Sharma and Shipra Mital Gupta
Original Research
The stability of nanofluid is the main challenge for their heat transfer applications. Stability means that dispersed solid nanoparticles in basefluid such as engine oil, ethylene glycol (EG), water do not aggregate at a significant rate. The addition of surfactant in basefluid is an excellent option to maintain the stability of nanofluid. This research’s major emphasis is in order to make stable nanofluid for thermal applications using different surfactants. Carbon nanotubes (CNT) nanoparticles are dispersed in water (DDW) with the help of SDS, GA and mixed surfactant (mixture of SDS and GA in 50:50 ratio) using a modified-two step method. Results showed that dispersion of CNT in basefluid was better at 1:1 surfactant/CNT ratio, 0.3 wt% of CNT concentration and 180 minutes (SDS), 150 minutes (GA), 90 minutes (mixed surfactant) ultrasonication time. Nanofluid prepared with SDS, GA and mixed surfactant were found to be stable upto about ~90 days, ~150 days and ~200 days, respectively. CNT nanofluid prepared with SDS, GA and mixed surfactant showed 33.9%, 46.3% and 54.3% enhancement in thermal conductivity as compared to DDW, respectively. According to the results, all three nanofluids can be used as a heat transfer fluid, but nanofluid prepared with mixed surfactant is more suitable because it showed higher thermal conductivity enhancement and better stability which are essential for heat transfer application.
World Journal of Chemical Education. 2022, 10(3), 95-104. DOI: 10.12691/wjce-10-3-2
Pub. Date: July 06, 2022
1878 Views4 Downloads
by R. Sanjeev and V. Jagannadham
Original Research
Hammett ρ values are estimated for the two acid dissociation equilibriums eqn. 1 and 2 of pyridinium and pyridazenium ions from the Hammett plots of log KaH versus Hammett σ values. The Hammett ρ values are found to be 5.94 and 5.29 for the two equilibriums eqns. 1 and 2 respectively. The effect of extra pyridine type nitrogen (=N-) on Hammett ρ is discussed. Similarly, the average lone pair ionization potentials (IP) of pyridines and pyridazines also followed Hammett equation with Hammett ρ of 1.18 for pyridines and 0.38 for pyridazines respectively. This article is useful in an undergraduate and graduate classroom who tries to study the substituent effects and reactivity-selectivity principle.
World Journal of Chemical Education. 2022, 10(3), 91-94. DOI: 10.12691/wjce-10-3-1
Pub. Date: June 23, 2022
2204 Views12 Downloads