Developing a project laboratory course in chemistry

During the redesign of the BSc degree structure at UNSW in 1998-1999, we set out to develop some third year chemistry courses which were not constrained by the conventional partitioning into ‘organic’, ‘inorganic’, ‘analytical’ and ‘physical’ chemistry designations. We also wished to provide all graduating students (in both three and four year degrees) with the opportunity to do project-based experimental work. Meanwhile, consultation with employer groups consistently highlighted team work, planning, organisational and communication skills as being highly desirable in graduates, but employers generally perceived science graduates to be deficient in some of these areas. We had previous experience of running problem-solving laboratories in an advanced analytical chemistry course and this came to serve as the pilot phase in the development of the new course. This paper describes the development of the project laboratory course in chemistry, its aims and outcomes, the feedback from students and how this influenced the further development of the course

Student-centred learning through a new investigative laboratory program in first year chemistry

A new laboratory program in chemistry has been designed, with the aim of fostering student-centred learning, critical thinking and problem-solving skills. The pilot phase is being introduced in 2003, initially for a class of 175 first year students, who have a good chemistry background and who have already completed one session of chemistry. We set out to offer our entry-level students the opportunity to appreciate that there are important unanswered questions in chemistry, to begin to ask their own scientific questions, to design and carry out experiments and to evaluate their results, in a problem-solving or research context. Group work was introduced both to foster a student-centred culture in the labs and to enable more significant experimental work to be undertaken. This initiative coincided with a university-wide first year experience project at UNSW in the development of graduate attributes, which is providing support for the project. This paper will report on the program design, assessment issues and initial evaluation of effects on student learning and motivation. The results of this project will eventually be used to extend the approach to much larger first year courses

A STUDY OF THE SYNTHESIS OF HYBRID ORGANOSILICATE NANOTUBES

Hybrid organosilicate nanotubes have been prepared by sol-gel chemistry, using crystalline ammonium tartrate as the tube-forming template. The nanotubes were prepared by controlled hydrolysis and co-condensation of tetraethyl orthosilicate (TEOS) and methyltriethoxysilane (MTES) at room temperature. The synthetic conditions have been systematically studied. The physical characteristics of the materials were examined by scanning electron microscopy (SEM) and the aging times of the tubes due to slow post-gelation condensation reactions was investigated. The morphology and microstructure of the nanotubes are greatly influenced by the synthetic conditions.   Keywords: organosilicate, nanotube, ammonium tartrate crystals

An investigative laboratory program in first year chemistry — experience and outcomes

A new laboratory program in first year chemistry was introduced in 2003, initially for a class of 200 students, with the aim of fostering collaborative student-centred learning and critical thinking. In the laboratory, students worked in teams, providing input into the design of some experiments and, towards the end of session they undertook a short experimental project. At the same time, the tutorial program was redesigned in order to introduce open-ended questions or questions with no single correct answer. The changes to the program were overwhelming successful, in that 78% of students reported the laboratory component to be either good, or the best thing about the course. While students found the new experimental approach challenging, and even frustrating at times, the tutorial modifications were less successful with 50% of students feeling that this section did not have the appropriate balance between conceptual and practical material. An important component of the change was to align the assessment with the goals of the new laboratory program. A higher proportion of marks were reallocated from lecture-based assessment to laboratory work, with some reduction in syllabus content. New assessment feedback sheets were designed to enable quality feedback to students and to enable demonstrators to provide consistent marks. This feedback mechanism has since been extended to other first year courses. The course was evaluated using an online student questionnaire, which allowed open comments, class visits and debriefing interviews with laboratory demonstrators and tutors. A number of further refinements have been identified, the most important of which are better structuring of tutorials and more support and training for demonstrators

Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) studies of corn at subzero temperatures

The physical states of water and its freezing behaviour in shelled corn during subzero drying were determined by using ²H NMR and ¹H MRI techniques. In this context, the ²H NMR spin–lattice relaxation times (T₁) and spin–spin relaxation times (T₂) of water in corn were measured. The relaxation times were found to decrease with decreasing temperature. The results revealed that there were two main water components in corn of >30% wb (wet basis) with long and short T₁. Both components exhibited minima around −20 °C. In more dehydrated corn (18.6% wb) only a single water component, with short T₁ and T₂ was observed. ¹H MRI images revealed the location of water and its freezing behaviour in different areas

Optical Study of the Near-Infrared Emission and Absorption in the Strongly Exchange-Coupled Dimer Cs3Mo2Cl9

Highly structured near-infrared emission has been observed from single-crystal CsMoClfor the first time, corresponding to the spin-allowedE“(AE) →A”(AA) pair transition. The spectroscopically determined singlet-triplet ground-state exchange splitting is approximately 842 cm, in excellent agreement with 840 ± 50 cmobtained from earlier ground-state magnetic studies. The emission spectrum is dominated by long progressions in the v(Mo-Mo) stretching mode of 111 cm, based on two static origins separated by 50 cm. The v(Mo-Mo) stretching mode is reduced some 31 cmfrom that of theA'(AA) ground state, indicating significant weakening of metal-metal bonding in theA”(AA) excited state. Band shape analysis results in Huang-Rhys parameters of approximately 2.8 and 3.6 for the two progressions, corresponding to lengthening of the Mo-Mo bond by approximately 0.09 and 0.10 Å, respectively. The large zero-field splitting of 50 cmobserved for theA”(AA) ground pair state is consistent with calculated values based on a perturbation treatment of the pair configuration in the Mo-Moσ bond limit. A temperature-dependence study of thick single crystals of CsMoClindicates that the entire 8000-cmabsorption band is due to theA(AA) →E”(AE) pair transition only, and this is consistent with the moderate Mo-Mo π interaction observed previously for the double-excitation region between 12 500 and 15 500 cm. From the spectroscopic analysis, the A' + A', E”, and E' spin-orbit levels of the 3E”(AE) multiplet were located with A' + A' established as the emitting level. At low temperatures, evidence exists for a small departure from strict D3selection rules