Unit 5
States of matter and gases.
The particle model: solid, liquid and gas, changes of state, where a gas's pressure comes from, and the gas laws.
The unit, lesson by lesson
Lessons
5 lessons · 25 practice questions · about 2 hours
The particle model
All matter is made of particles that never stop moving: how their arrangement and motion make a solid, a liquid and a gas, and why a gas takes a thousand times more room.
Changes of state
Melting, boiling, evaporation, condensation and sublimation: what happens to the particles in each change, where the energy goes, and why the temperature stands still while water boils.
Pressure and the gas laws
Where a gas’s pressure comes from, and three laws that follow from the particles: half the volume gives twice the pressure, twice the kelvin temperature gives twice the pressure, and twice the gas gives twice the pressure.
Molar volume
How many moles the box holds, how much room one mole of gas takes, and why a mole of hydrogen and a mole of carbon dioxide fill the same balloon.
Hydrogen, oxygen and nitrogen
Three colourless, odourless gases, and one test that tells them apart: a burning splint. And inside the jar: why hydrogen molecules move four times as fast as oxygen’s.