Ice floats in water because, unlike most substances, the solid phase of water is less dense than its liquid phase. When water freezes, it expands slightly, and the resulting change in density is enough to allow ice cubes to float in a glass of water.Know More
Ice's expansion at its freezing point is due to the polar structure of water molecules. In the liquid phase, water molecules are always in motion and can be packed closely together. As the temperature drops, however, the molecules begin to form hexagonal crystals. The hydrogen bonds created in these crystals arrange the molecules in such a way that more space exists between them than in the liquid phase, resulting in an expansion of around 8.3 percent in volume. Since the water the ice displaces now weighs less than the ice itself, ice is buoyant and floats.
This unique property is important to the development of life on earth. Because ice floats, rivers and streams form a layer of ice during winter. If water behaved like most other solids and became denser when cooled, this ice would fall to the bottom of each body of water, freezing it solid and killing any living things under the surface.Learn more about Thermodynamics
The energy required to change the temperature of a substance with no phase change is known as sensible heat. The change in temperature may come from the sun via the soil or the air.Full Answer >
Factors that affect evaporation include the concentration of the evaporating substances in air, temperature, air pressure, the rate of airflow and surface area. The heat of the sun facilitates the evaporation process, which is important in the water cycle.Full Answer >
Burning is a chemical reaction that involves the outer electrons of the substances. Usually, oxygen is one the elements, and something else that has excess electrons is the other. All chemical elements that aren't stable seek to become stable by the addition or subtraction of electrons. Oxygen needs two electrons to have a stable outer shell, and when it chemically reacts with a more electronegative substance, the result is fire.Full Answer >
When ice or any other solid melts, its potential energy increases. Indeed, this is the only increase in energy, since the thermal kinetic energy, or temperature, does not increase while melting. Potential energy is the latent energy that could be released by the water, and this increases because the water will release heat energy if it is frozen solid again.Full Answer >