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Types of Reactions

Types of Reactions

Author: carolyn fruin

Learning Targets:

  • I can explain what occurs in a synthesis/combination reaction, give its general equation and state how energy changes in combination reactions.
  • I can explain what occurs in a decomposition reaction, give its general equation and state how energy changes in decomposition reactions.
  • I can explain what occurs in a single replacement reaction and give its general equation and state how energy changes in single replacement reactions.
  • I can determine the products of given reactants in single replacement reactions using the information in the activity series and my knowledge of group 17.
  • I can explain what occurs in a double replacement reaction, give its general equation and state how energy changes in double replacement reactions.
  • I can state the conditions necessary for double replacement reactions to occur.
  • I can explain what occurs in a combustion reaction, give its general equation for hydrocarbons and state how energy changes in combination reactions.
  • I can state the possible products of incomplete combustion reactions and how this can be fatal.

Students can identify and predict the products of different types of reactions.

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Chemical Equations - Types of Reactions

Notes include types of reactions and the energy related to chemical reactions (chapter 17).



Chemical Reactions

In a chemical reaction, things are being mixed together or broken apart in some way to create a whole new set of things. It is important to remember that in a chemical reaction matter is neither created OR destroyed. The atoms of matter in a chemical reaction are simply rearranged to form new substances.

Chemical equations are written to explain what is happening in a chemical reaction. For example, the equation below shows what happens when zinc metal is combined with hydrochloric acid.

Zn (s) + 2 HCl (aq) --> ZnCl2 (aq) + H2 (g)
Zn and HCl are called the reactants because they are what will be reacting in this reaction. Zinc chloride (ZnCl2) and hydrogen gas (H2) are the products because they are what is produced from this reaction. The arrow separating the reactants and products means "yeilds". In other words, the above reaction reads "zinc combines with hydrochloric acid to yield zinc chloride and hydrogen gas." Notice the parentheses next to each reactant and product. The letter or letters inside the parentheses indicate what state of matter the reactant of product is in. A list of symbols that you may find in chemical reactions is listed below with their meanings.

  • (s) = solid
  • (aq) = aqueous solution
  • (g) = gas
  • (l) = molecular liquid

Types of Chemical Reactions


There are 5 types of chemical reactions: Synthesis, Decomposition, Single-Replacement, Double-Replacement,
and Combustion.
Synthesis Reactions: A + B --> AB
Decomposition Reaction: AB --> A + B
Single Replacement Reaction: A + BC --> AC + B
Double Replacement Reaction: AB + CD --> AD + BC
Combustion Reaction: Hydrocarbon + O2 --> H2O + CO2

Use the following list of question to determine what type of chemical reaction you are witnessing. When you can answer "yes" to a question, then stop!

  1. Does your reaction have oxygen as one of it's reactants and carbon dioxide and water as products? If yes, then it's a combustion reaction
  2. Does your reaction have two (or more) chemicals combining to form one chemical? If yes, then it's a synthesis reaction
  3. Does your reaction have one large molecule falling apart to make several small ones? If yes, then it's a decomposition reaction
  4. Does your reaction have any molecules that contain only one element? If yes, then it's a single displacement reaction
  5. If you haven't answered "yes" to any of the questions above, then you've got a double displacement reaction

Balancing Equations

When balancing equations, your goal is to make the number of atoms of each element be equal on the reactant and product side. This can ONLY be achieved by changing the coefficient numbers in front of each substance. NEVER EVER CHANGE THE SUBSCRIPTS IN CHEMICAL FORMULAS TO BALANCE AN EQUATION!

The following is an interactive tutorial to assist in your understanding of balancing equations: Balancing Equations Tutorial

Source: Richards-Chemistry

Predicting Products in a Chemical Reaction

This is a summary that may help you as you try to predict the products formed from a chemical reaction.