Chemical Reactions Part II- Ahmad Kilani

So we already discussed the first 3 types of reactions! Now we need to mention the remaining 3!


Double Replacement is one of them.

This is when the anions and cations of two different molecules switch places, forming two entirely different compounds. These reactions are in the general form:

 

AB + CD ---> AD + CB

One example of a double displacement reaction is the reaction of lead (II) nitrate with potassium iodide to form lead (II) iodide and potassium nitrate:

 

Pb(NO₃)₂ + 2 KI ---> PbI₂ + 2 KNO₃

 

The fifth reaction is Combustion. 

A combustion reaction is when oxygen combines with another compound to form water and carbon dioxide. These reactions are exothermic, meaning they produce heat.

An example of this kind of reaction is the burning of napthalene:

 

C₁₀H₈ + 12 O₂ ---> 10 CO₂ + 4 H₂O

 

And finally, the last reaction is Neutralization.

This is a special kind of double replacement reaction that takes place when an acid and base react with each other. The H⁺ ion in the acid reacts with the OH^- ion in the base, causing the formation of water. Generally, the product of this reaction is some ionic salt and water:

 

HA + BOH ---> H₂O + BA

One example of a neutralization reaction is the reaction of hydrobromic acid (HBr) with sodium hydroxide:

HBr + NaOH ---> NaBr + H₂O

Things to help you distinguish the difference between all of them:
Answer the following questions until you reach one with a "yes" answer:

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)  Does your reaction have water as one of the products? If yes, then it's a neutralization reaction

6)  If you haven't answered "yes" to any of the questions above, then you've got a double displacement reaction

Sample Problems (the solutions are in the next section)

List what type the following reactions are:
 

1)  NaOH + KNO₃ --> NaNO₃ + KOH
2)  CH₄ + 2 O₂ --> CO₂ + 2 H₂O
3)  2 Fe + 6 NaBr --> 2 FeBr₃ + 6 Na
4)  CaSO₄ + Mg(OH)₂ --> Ca(OH)₂ + MgSO₄
5)  NH₄OH + HBr --> H₂O + NH₄Br
6)  Pb + O₂ --> PbO₂
7)  Na₂CO₃ --> Na₂O + CO₂

 

Solutions to the Sample Problems

1)  Double Resplacement
2)  Combustion
3)  Single Replacement
4)  Double Replacement
5)  Neutralization
6)  Synthesis
7)  Decomposition