Hydrological cycle

Changes of State of Matter

The mass can occur in 3 states of matter - gaseous, liquid and solid.

The solid matter has a constant shape and volume. Solid matters are divided into crystalline and amorphous substances. A typical feature of crystalline substances is the regular arrangement of the particles (eg diamond, salt, various metals – copper, zinc, lead, etc.). Conversely, amorphous substances do not have a regular arrangement of particles (eg glass, wax). Liquid and gaseous substances can flow freely and adapt to the shape of the container. The change of state usually occurs by changing the temperature, i. cooling and heating. In literature we can also meet the so-called. the fourth state, which is called plasma. It is an ionized gas, which is composed of ions and electrons (or neutral atoms and molecules). It has no fixed shape and is capable of conducting electric current and responding to magnetic fields.

Phase transformation

When we change the state of matter from one to another we are talking about phase transformation. Some properties of substances, such as e.g. volume, density, thermal conductivity, etc.

Melting – when the object is made of a crystalline substance (e.g. ice, metal), its temperature increases. When the temperature reaches a certain temperature, called the melting point (different for different crystalline substances), the state changes from solid to liquid. The melting point of the crystalline substance depends on the external pressure. Upon heating the amorphous substance, the substances gradually soften and gradually turn into a liquid. Unlike crystalline substances, they do not have a certain melting point. For example, wood cannot be heated to the melting point – it decomposes. The melting point is lowered by dissolution of the salt. When the frozen sidewalk is sprinkled with salt, its melting point is lowered and the ice melts. During heating, most substances increase their volume. An exception is e.g. ice, which decreases its volume during heating and, on the contrary, increases during solidification.

Freezing – when cooling the liquid resulting from the melting of the crystalline substance, it changes at the freezing point to solid matter. However, the solid state does not form immediately. When the liquid reaches the freezing point, it gradually begins to form so-called solids. condensation cores, to which they gradually attach and regularly arrange other particles. The solidification of most substances reduces their volume.

Sublimation – it is the conversion of a solid into a gaseous substance, e.g. iodine, camphor, dry ice, without passing through the liquid state.

Reverse Sublimation – is the opposite process as sublimation. It is therefore a conversion of a substance from a gaseous state to a solid state. The gas is converted directly to a solid without condensation.

Vaporization – the conversion of a liquid to a gaseous that takes place on the surface of the liquid at any temperature at which the liquid state exists. The rate of evaporation depends on the type of liquid (for example, the ether evaporates most rapidly), the temperature (the rate of evaporation increases with increasing temperature) and the surface area of the surface. As the temperature rises, the evaporation rate also increases.

Condensation – the opposite of evaporation, i. change of gaseous state to liquid state. This change occurs e.g. when the temperature is lowered.