Ice melts in the sun, and water boils on a stove. A burn from steam is worse than a burn from boiling water. Here we learn what happens to the particles when matter changes state, how to measure the temperature in kelvin, and why heat can go in without a change of temperature.
3 lessons, about 1 h 20 min3 simulations10 problems6 practice questionsPython in every lesson
Created by StemPy LabWhen a solid is heated, its particles vibrate faster, and at the melting point it becomes a liquid. At the boiling point a liquid becomes a gas. The kelvin scale starts at the lowest possible temperature, and K = °C + 273.
While matter changes state, heat goes in or comes out without a change of temperature. This hidden heat is the latent heat. The heat for a change of state is the mass times the latent heat per kilogram.
Some solids change directly to a gas without becoming a liquid, which is sublimation, and the reverse, a gas changing directly to a solid, is deposition. Camphor, naphthalene, ammonium chloride, iodine and dry ice sublime, and sublimation can separate a substance that sublimes from one that does not. The state of a substance depends on temperature and pressure. A gas can be turned into a liquid by cooling and by compressing, as in the LPG cylinder. Above a certain temperature, no pressure can make a gas into a liquid. Heat goes in for melting, vaporisation and sublimation and comes out for the reverse changes.
Log in to join the discussion.
Loading…