MYP Chemistry · Particle theory of gases
Move the slider to add data points to the graph.
Use these after the diffusion and pressure tabs. The questions stay qualitative and MYP focused: trends, variables, graphs, misconceptions and particle explanations.
These are common weak answers. Rewrite each one so it explains what particles are doing.
"Gas particles get bigger when heated."
Correct it: The particles do not get bigger. They move faster because they have more kinetic energy.
"Pressure increased because there were more particles."
Correct it: Only say this if particles were added. In this simulation, pressure changes because collision frequency or collision force changed.
"Diffusion stops when particles are evenly spread."
Correct it: Particles keep moving randomly. There is no overall movement from one side to the other once they are evenly spread.
"Smaller volume makes particles hit harder."
Correct it: If temperature is constant, the particles do not hit harder. They hit the walls more often because there is less space.
Choose one:
1. Explain why diffusion is faster at higher temperature.
2. Explain why pressure increases when a gas is heated in a fixed container.
3. Explain why pressure increases when the volume of a gas is reduced at the same temperature.
This simulation supports MYP gas behaviour. Pressure and diffusion are explained using the particle theory of matter. Use this page as a quick reference.
A gas is made of very many particles spread far apart. The particles are in constant random motion in all directions. They have kinetic energy: the energy they have because they are moving.
The hotter the gas, the more kinetic energy the particles have, so the faster they move on average. The cooler the gas, the slower they move.
Particles collide with each other and with the walls of any container. These collisions are how a gas exerts pressure and how it spreads through its surroundings.
Diffusion is the spreading of particles from where they are more concentrated to where they are less concentrated, until they are evenly spread out.
Diffusion is faster when:
· The temperature is higher (particles have more kinetic energy and move faster).
· The particles are lighter (lighter particles move faster at the same temperature).
You do not need to do any calculations. Just describe the trend and explain it using particle motion.
Pressure is caused by gas particles colliding with the walls of their container. It depends on two things: how often the particles collide with the walls (frequency), and how hard they hit (force per collision).
Raising the temperature (with volume held constant) makes particles move faster. They hit the walls more often and with more force, so pressure increases.
Reducing the volume (with temperature held constant) means the same number of particles are now in a smaller space. They hit the walls more often, so pressure increases.
The energy a particle has because it is moving. Higher temperature = more kinetic energy.
How often particles hit the walls of the container in a given time.
Net movement of particles from high concentration to low concentration.
Force per unit area on the container walls, caused by particle collisions.
The variable you deliberately change in an investigation.
The variable you measure as a result.
A variable you deliberately keep the same so it does not affect the result.