Gases - Presentation

The presentation on gases begins with the objective of understanding how to draw and interpret particle diagrams of gases and how to identify a substance as a gas. These foundational questions set the stage for a deeper exploration into the properties and behaviours of gases within the realm of chemistry and states of matter. One of the key case studies discussed is the Bhopal Disaster of 1984, which highlights the dangers associated with gases. The incident involved the release of methyl isocyanate (MIC) gas from a chemical plant in Bhopal, India, leading to a catastrophic number of casualties and long-term health effects. This tragic event serves to illustrate the volatile nature of gases and the difficulty in controlling them, as well as the transition from liquid to gas when the storage tank was compromised, allowing the liquid MIC to evaporate and disperse rapidly through the air.

The presentation also delves into practical experiments and demonstrations to further the students' understanding of gases. One experiment shows that air, despite being invisible, has mass by observing the change in scale readings after blowing into a balloon. Another experiment involves the reaction between vinegar and bicarbonate of soda, which produces carbon dioxide, demonstrating how this gas can be utilized in fire extinguishers to put out flames by displacing oxygen. Additionally, the interaction of iron fillings with sulphur is used to explain the production of hydrogen sulphide gas, recognizable by its characteristic foul odour. The final activity challenges students to determine which carbonate produces the most carbon dioxide when reacting with an acid, using the weight of the beaker as an indicator of the gas produced. The presentation concludes by encouraging students to reflect on their learning, asking them to draw particle diagrams of gases, name various gases, and confirm their ability to identify substances in the gaseous state.