Question

у висновку дайте відповідь на запитання якою є істотна особливість хімічних явищ? які явища підтверджують, що хімічна реакція відбулася?

Answer 1

Відповідь:

істотна особливість хімічних явищ- перетворення речовин

хімічна реакція відбулася якщо:

1-вииділився газ

2-змінився колір

3- випав або розчинився осад

4-поява запаху

5-виділення тепла і світла

Пояснення:

Answer 2

The Essential Feature of Chemical Phenomena

The essential feature of chemical phenomena is the occurrence of chemical reactions. Chemical reactions involve the transformation of one or more substances into different substances with new properties. These reactions are characterized by the breaking and forming of chemical bonds between atoms, resulting in the rearrangement of atoms to create new molecules or compounds.

Chemical reactions can be observed in various ways, and there are several phenomena that indicate that a chemical reaction has taken place. These phenomena include:

1. Color Change: A change in color is often a visible indication that a chemical reaction has occurred. For example, when iron reacts with oxygen in the presence of moisture, it forms iron oxide, commonly known as rust. The formation of rust is accompanied by a change in color from metallic gray to reddish-brown.

2. Formation of a Precipitate: A precipitate is a solid that forms when two solutions are mixed together. The formation of a precipitate indicates that a chemical reaction has taken place. For example, when a solution of silver nitrate is mixed with a solution of sodium chloride, a white precipitate of silver chloride is formed.

3. Evolution of Gas: The evolution of gas is another indication of a chemical reaction. When certain substances react, they may release gas as a byproduct. For instance, when an acid reacts with a carbonate, such as when hydrochloric acid reacts with sodium carbonate, carbon dioxide gas is produced, which can be observed as bubbles.

4. Temperature Change: A significant change in temperature can also indicate a chemical reaction. Some reactions release heat energy, resulting in an increase in temperature, while others absorb heat energy, leading to a decrease in temperature. For example, the reaction between baking soda and vinegar produces carbon dioxide gas and is accompanied by a noticeable temperature change.

5. Light Emission: In some cases, chemical reactions can produce light. This phenomenon is known as chemiluminescence. One well-known example is the reaction between hydrogen peroxide and luminol, which produces a blue glow.

These phenomena provide evidence that a chemical reaction has occurred and are commonly used in chemical experiments and observations to identify and study chemical reactions.