Student Exploration: Boyle’s Law and Charles’s Law Vocabulary: absolute zero, Boyle’s law, Charles’s law, Gay-Lussac’s law, Kelvin scale, pressure Prior Knowledge Question (Do this BEFORE using the Gizmo.) A small helium tank measures about two feet (60 cm) high. Yet it can fill over 50 balloons! How can such a small tank contain enough helium to fill so many balloons? Gizmo Warm-up The Boyle’s Law and Charles’s Law Gizmo shows a container of gas. Inside, small purple spheres represent gas molecules. 1. Observe the particles. Are they all moving at the same speed? 2. How do the particles interact with the walls and lid of the container?
The Correct Answer and Explanation is:
Correct Answers:
Prior Knowledge Question:
A small helium tank can contain enough helium to fill so many balloons because the helium gas inside is highly compressed. When the gas is released, it expands rapidly, allowing a small volume of compressed gas to fill a much larger volume when it enters the balloons.
Gizmo Warm-up Questions:
- Are they all moving at the same speed?
No, the gas particles are not all moving at the same speed. They have varying speeds depending on their individual energy levels. - How do the particles interact with the walls and lid of the container?
The particles collide with the walls and lid of the container, exerting pressure on them through these collisions.
Explanation:
Gases behave in ways that can seem counterintuitive at first glance, especially when thinking about how a small helium tank can fill over 50 balloons. The explanation lies in the behavior of gas molecules and the scientific principles described by gas laws, particularly Boyle’s and Charles’s Laws.
Helium in a tank is stored under high pressure, meaning the gas molecules are tightly packed into a small volume. When the valve on the tank is opened, the pressure is released, and the helium expands. Gases naturally move from areas of high pressure to low pressure, so once released, the compressed helium rapidly spreads out, filling balloons that are many times the volume of the tank.
In the Gizmo, small purple spheres represent gas molecules. When observed, these molecules are in constant motion, but not all at the same speed. This reflects the kinetic theory of gases, which states that particles in a gas have a range of energies and speeds due to random motion.
As the particles move, they frequently collide with each other and with the walls and lid of the container. These collisions are what create pressure. The more frequent and forceful the collisions, the higher the pressure. This principle helps explain how a small amount of gas under high pressure can exert a significant force when released.
Overall, these gas behaviors explain why compressed helium in a small tank can expand enough to fill numerous balloons, all governed by gas laws and molecular motion.
