Double Displacement Flashcards
Double Displacement Pattern
The reaction on the previous slide is an example of double displacement
In this type of reaction, the cations of two different compounds trade places
The activity series is NOT used!
A double displacement reaction has takes place when any one of the following occurs
A solid (precipitate) forms
A gas is produced
Water is produced (through the process of neutralization)
Some ionic compounds can’t dissolve in water?
It turns out that some ionic compounds do not dissolve in water
An insoluble ionic compound product is called a precipitate
If theres no percipitates formed?
No Precipitate = No Reaction!
Two aqueous ionic compounds will only undergo a double displacement reaction if ONE of the products is a precipitate
How do we know if a precipitate forms??
We use the Solubility Table!
Double Displacement Reactions that Produce a Gas
Direct gas production:
ALL sulfide compound reactants produce H2S(g) when they react with an acid
Hydrogen sulfide is toxic and has a distinctive odour of rotten eggs!
Double Displacement Reactions that Produce a Gas
Hydrides
LiH (s) + H2O (l) 🡪 LiOH (aq) + H2 (g)
Hydrides react readily with water to produce hydrogen gas
Remember: treat water as H+OH-
Indirect gas production:
H2CO3(aq)
unstable!
Will break down into H2O (l) + CO2 (g)
Indirect gas production H2SO3 (aq)
Unstable!
Makes H2O (l) + SO2 (g)
Indirect gas production: NH4OH (aq)
Unstable!
Produces NH3 (g) + H2O (l)
Summary of Gas-Producing Double Displacement Reactions
Sulfides (e.g. Na2S) + Acid
Hydrogen sulfide, H2S
Remember, the reactants listed above must react with an ACID to produce the gas listed!
Summary of Gas-Producing Double Displacement Reactions
Carbonates (e.g. Na2CO3) + Acid
Carbon dioxide, CO2
Remember, the reactants listed above must react with an ACID to produce the gas listed!
Summary of Gas-Producing Double Displacement Reactions
Sulfites (e.g. K2SO3) + Acid
Sulfur dioxide, SO2
Remember, the reactants listed above must react with an ACID to produce the gas listed!
Summary of Gas-Producing Double Displacement Reactions
Hydride (e.g. LiH) + water
Hydrogen gas, H2
Summary of Gas-Producing Double Displacement Reactions
Ammonium salt (e.g. NH4Cl) + base
Ammonia, NH3
