which of the following undergoes change during a chemical reaction
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During a chemical reaction, the substances involved undergo various changes. Some of the changes that can occur include:
1. Changes in physical state: The substances involved in a chemical reaction can undergo changes in their physical state, such as from a solid to a liquid, a gas to a liquid, or vice versa. For example, when water boils and evaporates, it changes from a liquid to a gas.
2. Changes in color: Some chemical reactions can result in a change in color. This change in color can be either subtle or dramatic. For instance, when iron reacts with oxygen in the presence of moisture, it forms iron oxide, commonly known as rust, which has a reddish-brown color.
3. Formation of a precipitate: A precipitate is a solid substance that forms when two solutions react to produce an insoluble product. This can happen when two soluble substances are combined, and a new insoluble substance is formed. For example, when a solution of silver nitrate is mixed with a solution of sodium chloride, a white precipitate of silver chloride is formed.
4. Release or absorption of heat: During a chemical reaction, energy can be released or absorbed by the system. Exothermic reactions release heat, while endothermic reactions absorb heat. A common example of an exothermic reaction is the combustion of wood, where heat and light are released.
5. Evolution of gas: Some chemical reactions produce gases as products. These gases can be visible or invisible. For example, when an acid reacts with a metal carbonate, it produces carbon dioxide gas. This gas can be observed as bubbles forming in the reaction mixture.
These are just a few examples of the changes that can occur during a chemical reaction. It is important to note that not all changes mentioned here are observed in every chemical reaction, as the specific changes depend on the reactants, conditions, and type of reaction taking place.