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Lab Tips in Chemical Reactions

Here are some helpful tips to get through the next lab that asks to identify different types of reactions through experiment.

Chemical reactions can be grouped into one of six categories:

  1. Combustion: A combustion reaction occurs when oxygen reacts with another compound to form water and carbon dioxide. These reactions are exothermic, meaning that they produce heat.
  2. Synthesis: A synthesis reaction occurs when two elements or compounds combine to form a more complex molecule.
  3. Decomposition: A decomposition reaction is the opposite of a synthesis reaction, and occurs when a molecule breaks apart to form two elements or less complex molecules.
  4. Single displacement: Single displacement reactions occur when a single element reacts with a chemical compound and switches places with one of the elements in the compound.
  5. Double displacement: Double displacement reactions occur when the cations of two ionic compounds switch places.
  6. Acid-base: Acid-base reactions are simply double displacement reaction in which water is produced from the H+ ion from the acid and the OH- ion in the base.

Those definitions are all fine and dandy, but how do we identify what type of reaction is occurring? For example, let's say that we've been asked to determine the type of reaction that's taking place in a chemical process. To achieve this goal, read through the questions below in order. When you answer yes, STOP, drop, and roll. Well, at the very least stop and don't move on to the next question—you've found your final answer. If you answer no, continue to the next question.

Does the chemical equation contain oxygen, carbon dioxide, and water? If it does, it's a combustion reaction.

Do simple molecules combine to form a more complex molecule? If they do, it's a synthesis reaction.

Does a complicated molecule break apart to form two or more simpler ones? If it does, it's a decomposition reaction.

Are there any chemicals anywhere in the equation that consist of only one element, such as Fe, Na, H2, etc.? If so, it's a single displacement reaction.

Is water formed during this reaction? If so, it's an acid-base reaction.

If you've answered no to all of the above questions, it's a double displacement reaction.

We hope this helps! Good luck completing your next lab.

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