A Proposal for Teaching Chemical Equilibrium through Video Lesson Using a Tool of Daily Application

Background: Oral inflammatory ulcers are one of the common complaints of patients attending out-patient clinics. Previous in vivo studies had shown that an Aqueous M. citrifolia Fruit Extract (AMFE) possessed anti-inflammatory and ulcer healing activities. Therefore, a standardized topical bioadhesive gel containing AMFE-phytosome was developed and determined for its oral ulcer healing efficacy in a rabbit model. Methods: The AMFE phytosome (AMFE-P) was prepared by a complexation method with the required amount of AMFE: Phosphatidylcholine: Tween 80 to weigh ratio of 2:1:0.2. Poloxamer 407 was used as a gelling agent. The oral ulcer was induced in male New Zealand white rabbits by topical application of acetic acid. Each test compound was applied to the ulcer for 10 days beginning on the second day after the ulcer induction. Complete ulcer healing on the specimen obtained on day 12 was observed histologically using the histological scoring protocol. Results: The optimized gel containing AMFE-P equivalent to AMFE 10%w/w (10%AMFE-P gel) showed the best bioadhesive gel quality, a smooth and homogeneous texture with an optimum viscosity and pH range used in human oral cavity, a good physical and chemical stability and the highest percentage cumulative release of total phenolic and scopoletin content. It was found that a daily application of 10% AMFE-P gel exerted a superior ulcer healing efficacy and a significantly rapid ulcer healing process than a twice daily application of topical gel containing AMFE 10%w/w or chlorhexidine 0.2%. Conclusion: These findings demonstrated that 10% AMFE-P gel has potential as a safe and effective alternative therapeutic agent for oral ulcers.

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Developing a Three-Tier Diagnostic Instrument on Chemical Equilibrium (TT-DICE)

Educación Química ◽

10.22201/fq.18708404e.2020.3.72133 ◽

2020 ◽

Vol 31 (3) ◽

pp. 84

Author(s):

J. Jusniar ◽

E. Effendy ◽

Endang Budiasih ◽

S. Sutrisno

Keyword(s):

High School Students ◽

Chemical Equilibrium ◽

Diagnostic Instrument ◽

Difficulty Level ◽

Literature Study ◽

School Students ◽

Development Models ◽

High Category ◽

Third Stage ◽

Very High

<p class="p1"><span class="s1">This study aims to develop a Three-tier Diagnostic Instrument on Chemical Equilibrium (TT-DICE) to diagnose high school students’ misconceptions related to this topic. TT-DICE consists of thirty items, asking for students’ answers, reasonings, and levels of confidence. Three-stages development models developed by Treagust applied in developing TT-DICE. First-stage was a literature study to analyze the main concepts and students’ misconceptions in CE. The next step is the development of the TT-DICE prototype, consisting of item development, preliminary experiments, interviews, and revisions. The third stage of validity checking starts with content validation by experts and practitioners. A field test conducted to determine the reliability and quality variables are supporting TT-DICE items. These variables are Item Validity (IV), Difficulty Level (DL), Discrimination Index (DI), and effectiveness of distractors. Content validity by validators showed that the TT-DICE is valid with a very high category (96.1%). The results of item validity show that 88.9% of the items are valid. Testing of DL, DI, and the effectiveness of distractors in general, shows a good category. The Reliability of the three-tiers TTDICE using Alpha Cronbach is a high and very high category, respectively (0.83, 0.81 & 0.91). The overall validity test results also concluded if the TT-DICE is valid, reliable, and suitable to diagnose misconceptions of Chemical Equilibrium.</span></p>

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First passage time for the state of exact chemical equilibrium

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19800777 ◽

1980 ◽

Vol 45 (3) ◽

pp. 777-782 ◽

Cited By ~ 1

Author(s):

Milan Šolc

Keyword(s):

Chemical Equilibrium ◽

First Passage Time ◽

Passage Time ◽

The State ◽

Recurrence Time ◽

First Passage ◽

First Order ◽

The Mean ◽

Passage Times ◽

Number Of Particles

The establishment of chemical equilibrium in a system with a reversible first order reaction is characterized in terms of the distribution of first passage times for the state of exact chemical equilibrium. The mean first passage time of this state is a linear function of the logarithm of the total number of particles in the system. The equilibrium fluctuations of composition in the system are characterized by the distribution of the recurrence times for the state of exact chemical equilibrium. The mean recurrence time is inversely proportional to the square root of the total number of particles in the system.

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Chemical equilibrium and chemical kinetics

10.1093/oso/9780198782957.003.0014 ◽

2018 ◽

Author(s):

Dennis Sherwood ◽

Paul Dalby

Keyword(s):

Free Energy ◽

Equilibrium Constant ◽

Gibbs Free Energy ◽

Chemical Kinetics ◽

Chemical Equilibrium ◽

First Principles ◽

Effect Of Temperature ◽

Total System ◽

Free Energies

Building on the previous chapter, this chapter examines gas phase chemical equilibrium, and the equilibrium constant. This chapter takes a rigorous, yet very clear, ‘first principles’ approach, expressing the total Gibbs free energy of a reaction mixture at any time as the sum of the instantaneous Gibbs free energies of each component, as expressed in terms of the extent-of-reaction. The equilibrium reaction mixture is then defined as the point at which the total system Gibbs free energy is a minimum, from which concepts such as the equilibrium constant emerge. The chapter also explores the temperature dependence of equilibrium, this being one example of Le Chatelier’s principle. Finally, the chapter links thermodynamics to chemical kinetics by showing how the equilibrium constant is the ratio of the forward and backward rate constants. We also introduce the Arrhenius equation, closing with a discussion of the overall effect of temperature on chemical equilibrium.

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