Explain why smoke from a burning sofa could fill a room. - Leaving Cert Chemistry - Question c - 2016

The process by which smoke fills a room can be explained through the principles of diffusion and convection currents.

1. Diffusion: Smoke is made up of various gases that are released in high concentration at the source of the fire. These gases naturally move from areas of high concentration to areas of low concentration, seeking to equalize their levels throughout the space. Thus, as the smoke from the burning sofa enters the room, it disperses and diffuses rapidly into the surrounding air.

2. Expansion on Heating: When the sofa burns, the heat causes the gases to expand. This increase in temperature leads to an increase in volume, meaning the smoke will tend to rise and spread out, filling whatever space is available. Gases fill the volume of their containers, and in this case, the room acts as the container.

3. Convection Currents: As the warm smoke rises, it creates convection currents within the room. The warm air, being less dense, rises while cooler air moves in to occupy the lower space. This movement of air enhances the distribution of smoke throughout the room, allowing it to fill the space more effectively.