The world around us, with all its wealth anddiversity, lives according to laws that are fairly easy to explain with the help of such sciences as physics and chemistry. And even the basis of the vital activity of such a complex organism as a human is nothing else than chemical phenomena and processes.
Definitions and examples
An elementary example is a kettle set onthe fire. After some time, the water will begin to heat up, then boil. We will hear a characteristic hiss, streams of steam will fly out of the neck of the kettle. Where did he come from, because in the bowl it was not originally there! Yes, but water, at a certain temperature, begins to turn into a gas, changes its physical state from liquid to gaseous. Those. it remained all the same water, only now in the form of steam. This is a physical phenomenon.
And we will see chemical phenomena if we omit it inboiling water tea bag. Water in a glass or other vessel will turn reddish-brown. A chemical reaction will occur: under the influence of heat, the tea leaves will begin to steam up, highlighting the color pigments and taste properties of this plant. We will have a new substance - a drink with specific quality characteristics peculiar only to it. If we add a few spoons of sugar there too, it will dissolve (physical reaction), and the tea will become sweet (chemical reaction). Thus, physical and chemical phenomena are often interrelated and interdependent. For example, if the same tea bag is placed in cold water, the reaction will not occur, the tea leaves and water will not interact, and the sugar will not dissolve either.
Thus, chemical phenomena are those in which some substances are converted into others (water into tea, water into syrup, firewood into ashes, etc.) Otherwise, a chemical phenomenon is called a chemical reaction.
Physical are the phenomena in whichthe chemical composition of the substance remains the same, and the state of aggregation, body size, shape, etc., change. (deformed spring, water frozen in ice, tree branch, broken in half).
Conditions of occurrence and course
Whether chemical and physical occurphenomena, we can judge by some signs and changes that are observed in a particular body or substance. So, the majority of chemical reactions are accompanied by the following "identifying marks":
- as a result or during the course of such a precipitate falls out;
- a change in the color of the substance occurs;
- gas may be released, for example, carbon monoxide during combustion;
- absorption or, conversely, heat release occurs;
- possible emission of light.
For chemical phenomena to be observed, i.e. reactions occurred, some conditions are necessary:
- the reactants should be in contact, be in contact with each other (i.e., the same tea should be poured into a mug of boiling water);
- it is better to grind the substances, then the reaction will proceed faster, rather the interaction will occur (granulated sugar is more likely to dissolve, melt in hot water than lumpy);
- in order for many reactions to occur, it is necessary to change the temperature mode of the reacting components, cooling or heating them to a certain temperature.
You can observe the chemical phenomenon empirically. But you can describe it on paper using a chemical equation (chemical reaction equation).
Some of these conditions work forthe occurrence of physical phenomena, for example, a change in temperature or direct contact of objects, bodies with each other. Suppose if you hit a nail head hard enough with a hammer, it can deform, lose its usual shape. But she will remain a nailhead. Or, when the light bulbs are turned on in the network, the tungsten filament inside it will begin to heat and glow. However, the substance from which the thread is made, will remain the same tungsten.
The description of physical processes and phenomena occurs through physical formulas, the solution of physical problems.
