Question

From what observations can you conclude that a chemical change is occurring

Answer 1

Explanation:

Chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. Some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. Understanding chemical changes is a major part of the science of chemistry.

When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an energy change as new products are generated. An example of a chemical change is the reaction between sodium and water to produce sodium hydroxide and hydrogen. So much energy is released that the hydrogen gas released spontaneously burns in the air. This is an example of a chemical change because the end products are chemically different from the substances before the chemical reaction.

Answer 2

Chemical Change

A chemical change is the transformation of one material into another, the formation of new materials with different properties, and the formation of one or more new substances.

It occurs when one substance reacts with another to form a new substance (synthesis or decomposition to form more substances). The oxidation reaction is an example of a chemical change that results in a chemical reaction.

Except through further chemical reactions, they are generally irreversible. Examples of chemical changes include the chemical reaction that develops the dye in colour and causes a chemical change in the hair. Organic, inorganic, and biochemical changes are the three types of chemical changes.

Chemical Changes in Everyday Life

Chemical changes occur all around us, not just in chemistry labs. Some examples of chemical changes in our daily lives are provided below.

• Paper and wood log burning
• Food digestion
• Cooking an egg
• Metal electroplating
• Cake-making
• Milk has gone sour
• Fruits rotting
• Iron corrosion
• Lighting a matchstick

Chemical Change Characteristics

• The generation of heat, light, or sound
• The gas formation that is not present in the reactants
• A permanent colour change
• Precipitation formation
• Changes in odour or flavour
• Density change
• Temperature change

Chemical Change Types

• When two or more substances combine to form a new substance, this is called chemical synthesis or combination.
• Chemical decomposition occurs when a substance breaks down into two or more different substances.
• When atoms or molecules form or break bonds, chemical reactions occur. Heat or thermal radiation can be absorbed or released in both cases. An exothermic reaction produces heat, and endothermic reactions require heat.

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