Physical phenomena are those events or events where the composition of the material is not modified, that is, it maintains its physical properties. Chemical phenomena are those events that occur due to alterations in the composition of matter.
We get physical and chemical phenomena in our day to day, from boiling water, frying an egg to the blue color of the sky. Physics and chemistry are the sciences that allow us to explain all these phenomena.
|Definition||Events that occur without affecting the molecular composition of matter.||Events that occur due to changes in the molecular structure of matter.|
Compounds stay the same
new compounds are produced
|Types|| || |
|examples|| || |
What are physical phenomena
Physical phenomena are events that occur in nature in which the composition of matter is not altered. These phenomena can be explained by the laws of physics. Here are some examples of physical phenomena.
When a jet breaks the sound barrier, it produces sound waves that are like explosions.
The sound barrier is a physical acoustic phenomenon resulting from the collision of sound waves in the air. Sound is a wave that travels through the air at a speed of 343 meters per second. When an airplane exceeds this speed, a noise similar to an explosion is produced. This is known as “breaking the sound barrier.”
The rainbow in the sky where all its colors are distinguished.
The rainbow is a luminous physical phenomenon that we can observe in the sky when the light of the Sun is reflected and refracted in the raindrops. The water droplets act in this case as a prism, separating the bands of colors that make up the light.
We can often have the illusion of a puddle of water in the distance on a road when it is very hot.
A mirage is a physical-optical phenomenon that occurs because light bends as it passes through layers of air with different temperatures. It is an optical illusion that makes us perceive the presence of water in the distance, which is not real.
Telecommunication fiber optic coil illuminated by a green laser light.
Optical fibers are an optical physical phenomenon characterized by the fact that light travels through long glass or plastic cables or fibers. This happens because the light is reflected internally in the cable, which causes it to bounce throughout the fiber without being lost in the external environment. They are widely used for the transmission of data, images and sound.
You may also be interested in knowing about reflection and refraction of light.
Lightning or thunderbolts are electromagnetic phenomena that occur in the atmosphere. They are electrical discharges that generally occur during storms. This is due to a separation of electrical charges between the earth’s surface and the clouds. When lightning occurs, such an amount of energy is released that it lights up the sky and generates heat.
What are chemical phenomena?
Chemical phenomena are the events that occur when the composition of matter is altered. In everyday life we come across different chemical phenomena that sometimes go unnoticed. Here are some examples of chemical phenomena.
The different colors seen in fireworks are due to their different compounds.
Fireworks are chemical phenomena that are produced by the heating of metals in an explosion. For example, strontium produces a deep red color, sodium produces a yellow color, copper produces a green color, and potassium produces a lilac color.
When iron materials are left outdoors they oxidize producing rust.
Rust is a chemical phenomenon that we find in iron materials or other metals as a result of oxidation and reduction reactions. This phenomenon involves the chemical transformation of iron to iron oxide in the presence of oxygen, either from air or water, with the characteristic light brown color.
The purple and blue areas over Antarctica correspond to the lowest concentrations of ozone in the Earth’s atmosphere.
The ozone hole is the result of the decrease in ozone (O3) levels in the atmosphere, due to chemical reaction with compounds known as chlorofluorocarbons (CFCs). O3 is a molecule found in the atmosphere that protects the planet against ultraviolet rays from the Sun.
CFCs are compounds initially used as refrigerants and in aerosols. Once in the air, the CFCs react with oxygen and the ozone disappears. The atmosphere at the level of the Antarctic region has the lowest concentration of ozone, which is popularly known as the ozone hole.
Effects of acid rain on a statue exposed to the elements (Attribution: Nino Barbieri / CC BY-SA).
Acid rain is a chemical phenomenon resulting from increased acidity in rainwater due to air pollution. Industrial processes produce gaseous sulfur dioxide, which reacts with rainwater to form sulfuric acid, a strong acid that is highly corrosive.
Another polluting gas is nitrogen oxide (IV) which reacts with water to form nitrous acid (HNO2) and nitric acid (HNO3).
Acid rain has detrimental effects on the environment:
- Alteration of the pH of aquatic environments.
- mineral dissolution.
- Corrosion of metals and constructions.
color of hydrangeas
Hydrangeas (Hydrangea macrophylla) are blue or pink depending on the pH of the soil.
The color of the sepals of hydrangeas (Hydrangea macrophyla) is a chemical phenomenon produced by the pH of the soil:
- In acid soils (less than 7): the sepals are blue.
- On basic soils (greater than 7): the sepals are pink/purple.
This is due to the solubility of aluminum in water at acidic pH, which allows the absorption of this element by plants. As a result, the aluminum binds to the anthocyanin pigment in the sepals, producing the blue color.
At neutral (7) or basic (greater than 7) pH, aluminum is insoluble in water, so it cannot be absorbed by plants. In this way, the color of the hydrangea sepals depends on anthocyanin, which is naturally a purple pigment.
You may be interested in seeing Natural Phenomena.