--- title: Melting, freezing and boiling — a lesson of Mova's school · trees and pragmatics description: «Melting, freezing and boiling», a lesson of the world course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: When a solid is heated enough, its particles move so much that they break free from their places and it becomes a liquid: this is melting. --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [World](https://md.mova.elamur.ai/free/en/corpora/school/world/) / Melting, freezing and boiling # Melting, freezing and boiling Lesson 12 of the world course of Mova's primary school: 17 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/world/12-melting-freezing-boiling/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/0/) — When a solid is heated enough, its particles move so much that they break free from their places and it becomes a liquid: this is melting. - [1](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/1/) — When a liquid cools enough, its particles slow down and lock into place: this is freezing. - [2](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/2/) — Pure water freezes at 0 °C, and ice melts at the same temperature, 0 °C. - [3](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/3/) — When a liquid is heated strongly, bubbles of gas form inside it and it boils; pure water boils at about 100 °C at sea level. - [4](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/4/) — These are changes of state: the substance stays the same, only the way its particles are arranged changes, and the change can be reversed. - [5](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/5/) — For example, chocolate melts in a warm hand and goes hard again in the fridge, but it is still chocolate. - [6](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/6/) — Melting is a solid turning into a liquid. - [7](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/7/) — Freezing is a liquid turning into a solid. - [8](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/8/) — Pure water freezes at 0 °C and boils at about 100 °C at sea level. - [9](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/9/) — While ice is melting, it stays at 0 °C until all of it has melted. - [10](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/10/) — While water is boiling, it stays at about 100 °C however strongly it is heated. - [11](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/11/) — Different substances melt at different temperatures: butter melts in a warm room, but iron needs about 1500 °C. - [12](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/12/) — Lava from a volcano is rock so hot that it has melted into a liquid; when it cools it freezes back into solid rock. - [13](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/13/) — Water expands when it freezes, so ice takes up more space than the water it came from. - [14](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/14/) — Changes of state can be reversed; burning and cooking cannot. - [15](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/15/) — The bubbles in boiling water are water vapour, not air. - [16](https://md.mova.elamur.ai/free/en/corpora/school/world/12-melting-freezing-boiling/16/) — High up in the mountains water boils below 100 °C, because the air pressure there is lower: the air is thinner and presses down less on the water. - ← previous: [Solids, liquids and gases](https://md.mova.elamur.ai/free/en/corpora/school/world/11-solids-liquids-gases/) - next →: [Evaporation and condensation](https://md.mova.elamur.ai/free/en/corpora/school/world/13-evaporation-condensation/) - ↑ back to [World](https://md.mova.elamur.ai/free/en/corpora/school/world/)