Types of chemical reactions

Types of chemical reactions

Lessons

• Many chemical reactions can be categorized because of the reactants they use or the products they form. There are many types including neutralization, combustion, displacement, decomposition and metathesis.

Neutralization reactions are identified by the use of an acid and an alkali.

• Along with water, a neutralization reaction will produce a salt, comprised of the metal ion(s) of the alkali and the negative ion(s) of the acid involved. These are the remaining compound fragments that did not form water.

Combustion reactions are defined by the use of oxygen gas to react with one other chemical. Combustion of hydrocarbons is a very common reaction, and is how most cars generate power.

Displacement reactions involve an atom or groups of atoms being exchanged or ‘swapped’ from a chemical compound.

• Displacement reactions involve a metal (or non-metal) in elemental form e.g. Mg (or Cl$_2$) and a metal (or non-metal) in a salt (e.g. ZnBr$_2$) where the two metals (or non-metals) exchange.

Metathesis reactions involve atoms or groups of atoms being exchanged between two different chemical compounds containing both metal and non-metal ions. It is similar do a displacement reaction except two compounds are involved, not one.

Decomposition reactions involve one chemical compound reactant breaking down into two or more products which were originally part of the starting compound.

• Decomposition reactions are easy to spot – they normally only have one reactant which is the compound that is decomposing!

In this lesson, we will learn:
• To analyze chemical reactions in terms of the reactants and products involved.
• To understand the value of categorizing reactions in chemistry.
• To predict the products of chemical reactions based on the reactants involved.
• 1.
Spotting chemical patterns
a)
Why and how we categorize reactions.

b)
Reaction type: Neutralisation.

c)
Reaction type: Combustion

d)
Reaction type: Decomposition.

e)
Reaction type: Displacement

f)
Reaction type: Metathesis.

• 2.
Recall the main types of chemical reactions and how to identify them.
Four reactions are shown below:
Reaction 1: C$_5$H$_{12\;(l)} +$8 O$_{2\;(g)}$→5 CO$_{2 \;(g)} +$6 H$_2$O$_{\;(g)}$
Reaction 2: ZnSO$_{4\;(aq)} +$Mg$_{\;(s)}$→MgSO$_{4\;(aq)} +$Zn$_{\;(s)}$
Reaction 3: CaCO$_{3\;(s)}$→CaO$_{\;(s)} +$CO$_{2\;(g)}$
Reaction 4: AgNO$_{3\;(aq)} +$NaCl$_{\;(aq)}$→AgCl$_{\;(s)} +$NaNO$_{3\;(aq)}$
a)
Which of the reactions is a metathesis reaction? Explain how you know.

b)
Which of the reactions is a displacement reaction? Explain how you know.

c)
Which of the reactions is a decomposition reaction? Explain how you know.

• 3.
Balance equations and identify the type of reaction taking place.
Balance and categorise the following equations:
a)
H$_2$SO$_4 +$NaOH→Na$_2$SO$_4 +$H$_2$O

b)
Ca(NO$_3$)$_2$→CaO$+$NO$_2 +$O$_2$

c)
Cl$_2 +$NaBr→NaCl$+$Br$_2$

• 4.
Apply knowledge of reaction types to predict products, balance equations and categorise the reaction.
Complete and balance the reaction equations, then categorise them.
a)
BaCl$_2 +$Na$_2$SO$_4$

b)
NO$_2$

c)
C$_6$H$_{14}+$O$_2$

d)
Ba(OH)$_2 +$H$_2$SO$_4$