What are the clues that a chemical reaction has taken place?

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There are a number of clues that a chemical reaction has taken place. If any of them are observed, we can surmise that a chemical reaction has taken place. Some of these clues are:

  • Production of gas: a number of chemical reactions result in the generation of gas (or gases)....

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There are a number of clues that a chemical reaction has taken place. If any of them are observed, we can surmise that a chemical reaction has taken place. Some of these clues are:

  • Production of gas: a number of chemical reactions result in the generation of gas (or gases). Thus, a visual observation of gas generation is a clue to a chemical reaction.
  • Heat change: A number of chemical reactions either need energy for completion or generate energy upon completion. Thus, if the reaction container gets hot or cold, this change in temperature of the container is a clue that a reaction has taken place.
  • Change in color: A number of chemical reactions are accompanied by a color change, which is another clue.
  • Smell or odor: A number of chemical reactions result in compounds that produce a smell, which can be used as another clue.
  • Precipitate formation: A number of chemical reactions produce precipitates. Thus, if we observe some precipitate formation and settling, we can be sure that a chemical reaction has taken place.

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