What are chemical equations 1

Chemical reactions (simple examples)

Chemical reactions are a big problem for many students. We want to describe what is actually hidden behind such a chemical reaction equation using a few simple examples. This article belongs to the basics of chemistry.

In this section I want to explain some simple chemical reactions to you. I will go into the important fundamentals of chemistry again in a moment in order to understand exactly these relationships. However, if you have any major gaps in your previous knowledge, I advise you to read the following articles first:

Chemical reactions video:
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  • Notes: This is still a blackboard video. A New edition in HD is planned. You can also access it directly in the Chemical Reactions Video section.
  • Problems: If you have playback problems, please go to the article Video problems.

Understanding chemical equations

Everyone (should) know it from mathematics: 2 + 3 = 5. That means: The value on the left side of the equation is the same as on the right side of the equation. There are also equations in chemistry, so-called reaction equations. However, these work a little differently. First of all, there are two "meaningful" forms, one equation to set up in chemistry. The first is a notation made up of words (word equation). This has the advantage that even people less versed in chemistry can understand the equation. Anyone who is fitter in chemistry describes chemistry Reaction equation.

Example 1:

  • Text notation: copper + oxygen → copper oxide
  • Reaction equation: 1Cu + 1O → Cu1O1

The first thing we have here is the text notation for the reaction: It says that copper and oxygen become copper oxide. Below the whole thing was written down in a "chemical notation". This means that a copper atom (Cu atom) with an oxygen atom (O atom) becomes a copper oxide unit.

First of all, try to remember the following (hopefully a few more examples will help you understand): The numbers in front of the symbols - that is, the capitalized numbers - are called Coefficients designated. These indicate how many of the particles are converted during the reaction. The small numbers - also called the index - indicate how many atoms there are in the respective substance.

Before we get to further examples, a few more important terms: On the left side of the equation are the Raw materials, also Educts called. The arrow is called Reaction arrow and indicates in which direction the reaction takes place. If this points in both directions, the reaction can also take place in both directions. On the right is the result of the reaction, too Products called.


More chemical reactions

I hope you have already memorized something from above. Hopefully a few more examples will provide a correct understanding. Two small definitions should not be withheld from you: A molecule is a particle that consists of two or more atoms. An ion is an electrically charged atom or molecule. You don't need to pay too much attention to that now, I just don't want to receive emails of the type "I don't even know the word".

Example 2:

  • Sodium + chlorine → sodium chloride
  • 2Na + 1Cl2 → 2NaCl

Explanation: The equation states that 2 sodium atoms and 1 molecule of chlorine consisting of 2 chlorine atoms react to form sodium chloride 2NaCl. Caution pitfall: The result 2NaCl says that the reaction produces 2 sodium ions and 2 chloride ions and not (!!!) two molecules of sodium chloride!

Example 3:

  • Nitrogen + hydrogen → ammonia
  • N2 + 3H2 → 2NH3

Explanation: 1 molecule of nitrogen consisting of 2 nitrogen atoms and 3 molecules of hydrogen with 2 hydrogen atoms each become ammonia. The ammonia consists of 2 nitrogen atoms and 2 · 3 = 6 hydrogen atoms.

Control tip for chemical equations

There is a little "trick" how you can check chemical reactions for correctness. Because the number of atoms has to be the same on both sides of the chemical equation. We will show you this control of the atomic numbers for the three examples. First of all, I'll give you the equation from above. For a better overview, I write all the numbers to the equation again, i.e. also the "individual" ones that are often left out. Then the number of atomic bills:

  • Original equation: 1Cu + 1O → Cu1O1
  • A bit rewritten: 1Cu1 + 1O1 → 1Cu11O1
  • Atom calculation: 1 1 + 1 1 → 1 (1 + 1)
  • Atom calculation: 2 → 2
  • Original equation: 2Na + 1Cl2 → 2NaCl
  • A little rewritten: 2Na1 + 1Cl2 → 2Na1Cl1
  • Atom calculation: 2 1 + 1 2 → 2 (1 + 1)
  • Atom calculation: 4 → 4
  • Original invoice: N2 + 3H2 → 2NH3
  • A little rewritten: 1N2 + 3H2 → 2N1H3
  • Atom calculation: 1 2 + 3 2 → 2 (1 + 3)
  • Atom calculation: 8 → 8


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