Understanding of Kinetic Molecular Theory of Gases in Three Modes of Representation among Tenth-Grade Students in Chemistry

An analysis of students’ performance in Kinetic Molecular Theory (KMT) of gases was done to determine the extent of the understanding of these chemistry concepts in three modes of representation, namely macroscopic, microscopic, and symbolic. The study employed one-shot quasi-experimental research where students in Grade 10 at a secondary school in Cebu City were exposed to the Integrated Macro-Micro-Symbolic Approach (IMMSA). A validated post-test tool with macro, micro, and symbolic questions was used in the study. The post-test results revealed that there was a gradual improvement of the students’ understanding from a good understanding of macroscopic and microscopic levels to a very good understanding of the symbolic level. Thus, it was concluded that the use of three modes of chemical representation led to a high extent in the understanding of concepts in chemistry. It is recommended that teachers begin their instruction at the macroscopic level and introduce symbols only after the microscopic level.

The more they enjoy it, the better they learn it !

<p>                                               Overcome Misconceptions and Provide Permanent Learning   </p><p>      As being an elementary science teacher for over ten years, I have observed that students learn best when they are active and enjoy when they like the topic. However, I have also observed that they can easily forget what they have learnt or can learn in the wrong way. I try to organize my lessons in the way that provide permanent learning or prevent misconceptions. For example, in order to teach concept of balanced and unbalanced forces and teaching the properties of force I usually let my students play tug of war outside of classroom, then they argue the size of the force and the direction of the force and the results. Similarly, in order to teach the topic calculation of average velocity, I also let my students to discover velocity outside of classroom, in this activity, the students gather data as a class from a person running at different rates on a school garden or football field and then they calculate the average velocity of their friends and create a distance versus time graph with data they collected. Moreover, in other to teach the basics of the kinetic molecular theory: properties of solids, liquids and gases, I let my students animate matter’s particles that are constantly in motion in company with the music which goes  from slow to upbeat music. In addition it can be hard to teach to my students the motion of the Sun, Earth and the Moon the relationship between the three and in particular to show eclipses. In order to make this concept understandable for them, they build a “Tellurion” that is model of The Earth, the Sun and the Moon as a long term project.</p><p> As a result, at the end of all these activities, students can learn easily, permanently and also enjoy. While doing such as activities I try to catch the misconceptions and correct them as possible as I can do. I’m planning to demonstrate in my poster such examples of activities and my students’ reactions to them and share with my colleagues from other countries as well as, I planning to ask for alternatives ways in such topics they use in their lessons.</p>

Dalton’s and Amagat’s laws fail in gas mixtures with shock propagation

A shock propagating through a gas mixture leads to pressure, temperature, and density increases across the shock front. Rankine-Hugoniot relations correlating pre- and post-shock quantities describe a calorically perfect gas but deliver a good approximation for real gases, provided the pre-shock conditions are well characterized with a thermodynamic mixing model. Two classic thermodynamic models of gas mixtures are Dalton’s law of partial pressures and Amagat’s law of partial volumes. We measure post-shock temperature and pressure in experiments with nonreacting binary mixtures of sulfur hexafluoride and helium (two dramatically disparate gases) and show that neither model can accurately predict the observed values, on time scales much longer than that of the shock front passage, due to the models’ implicit assumptions about mixture behavior on the molecular level. However, kinetic molecular theory can help account for the discrepancy. Our results provide starting points for future theoretical work, experiments, and code validation.