The history and development of Fourier transform ion cyclotron resonance mass spectrometer (FT ICR MS) is presented in detail. The dissociation technique for tandem mass spectrometry and the latest application are introduced. The development trend of FT ICR MS is discussed.
This paper probes into the differences between undergraduate and postgraduate in teaching content and mode of environmental chemistry. It puts forward that undergraduate teaching is based on teaching the basic theory, with pollution incident as the breakthrough point. Undergraduate teaching emphasizes systematicness, interestingness and characteristic, adopting methods of problem teaching, case teaching and video teaching. However, postgraduate teaching mainly sums up knowledge points, focus on the research hotspot and frontier problems and emphasizes bridging, initiative and applicability. It adopts methods of interactive teaching, experience teaching and literature induction, etc.
The graduation thesis is an important step for the student to develop creative thinking, comprehensive ability and engineering practice ability. Using the graduation thesis of applied chemistry major at Xi'an University of Technology as an example, this paper provides an overview of the process management executed in the steps of the graduation thesis for improving the quality of the graduation thesis.
This paper describes the basic functions and features of chemical equilibrium diagram software HYDRA/MEDUSA. The application to four types of chemical equilibria, including the precipitation equilibrium, the acid-base equilibrium, the coordination equilibrium and the redox equilibrium, is illustrated. It shows that HYDRA/MEDUSA software is helpful in learning the complicated equilibrium calculations and understanding the governing factors for chemical reactions. This software can also be used for researches involving chemical equilibrium calculations as well as species distribution calculations.
Innovation experiments for undergraduates are important part of the teaching reform, and also are important approaches for improving the quality of university education and overall qualities of undergraduates. Through examples, the article illustrates the role and significance of developing innovation experiments for tuition-free normal university students majored in chemistry.
Quantum yield is an important parameter in photochemistry. Diarylethene, as a kind of photochromic compound, is used in the experiment. We have validated the method for measuring the quantum yield in the photochemical reaction using the in-house made setup and applied this experiment to the comprehensive laboratory course. This experiment facilitates a better understanding of the principles and the applications, and the students' ability and interest to conduct an experiment are improved.
This experiment combines the principles and basic operations of physical chemistry and organic chemistry, in which the Brønsted acidic ionic liquid is used as the catalyst for the preparation of n-butylacetate for learning the principles of chemical kinetics, the kinetic equations and related calculations. The results show that the assumption of kinetic equations is consistent with the experimental results. The experiment reflects the results of the recent scientific research with easy operability, which will motivate the students and improving their learning ability and practical ability. It is worthy of recommendation as an experiment in the physicochemical comprehensive laboratory.
This paper introduces the data fitting method for determination of the surface tension of n-butanol solution, and a software program was developed with MATLAB for the model fitting. With this software it is convenient to obtain the equation describing the relationship between the surface tension (σ) and the concentration (c) of n-butanol based on the Szyszkowski model. The surface excess (Γ) can be calculated subsequently, and the saturation surface excess (Γ_{∞}) and cross section area of n-butanol solution can be obtained by extrapolation.
In this paper, the saturated vapor pressure of ethanol is measured by both the static and the dynamic methods. A comparison of these two methods is provided for the understanding and further improvement of this experiment.
Organic chemistry is the core course of chemistry, biology and medicine, and other disciplines. The textbook Fundamental Organic Chemistry (Higher Education Press) is adopted by many universities. We proposed amendment for two mechanisms in this book involving the radical anion intermediate, the alkynes reduction with alkali metal in liquid ammonia and the Birch reduction.
Alkali metal in liquid ammonia is widely applied in organic synthetic chemistry as a strong reducible reagent. Reduction reactions with alkali metal such as converting alkynes to olefins and Birch reactions are detailed described before. Here, we discuss its mechanisms further according to recent published literatures.
There are two ways to calculate the chemical potential of a component in solution. One is that, in the gas-liquid phase equilibrium, the chemical potential of a component in solution is equal to its corresponding chemical potential in the gas phase; thus, the chemical potential of the component in solution can be easily obtained through the gas-liquid equilibrium once its chemical potential in gas phase is known. Another way is to integrate directly the total differential of the chemical potential of the component in solution. Based on this, a new way to derive the osmotic pressure equation is presented in this article. It is also pointed out that the definitions about the osmotic pressure in some domestic physical chemistry textbooks are not reasonable and the derivation of the osmotic pressure equation is not valid.
Based on the thermodynamic properties of ions in solution, we modified the Debye-Hückel expression. The modified expression could be well correlated with the mean activity coefficients of different strong electrolyte aqueous solutions with various ionic charges, and the applicable concentration range is extended to 6mol·kg^{-1}.
In this paper, the change of entropy function (S) in the process of gas throttling expansion has been explored. It has been pointed out that the entropy change associated with the throttling expansions of any gases is always positive, and that the process is irreversible. The total thermodynamic characteristics of throttling expansions have been systematically discussed and summarized. The content involved is of importance in the teaching practice for students to gain better insights into the characteristics of the irreversible process, the function of entropy and the principle of entropy increase, as well as the relationships among all thermodynamic functions.
In this paper, redox titration functions were derived by mass balance theory and Ringbom's side reaction approach. Origin software was used to solve the functions and plot redox titration curves.
A universal formula of crystal plane distance (d_{(hkl)}) was obtained by using two different mathematical methods, and the formulae d_{(hkl)} for other lattice systems were deduced based on the proposed method.