Double Displacement

Question 1

Double Displacement Pattern

Answer 1

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!

Question 2

A double displacement reaction has takes place when any one of the following occurs

Answer 2

A solid (precipitate) forms
A gas is produced
Water is produced (through the process of neutralization)

Question 3

Some ionic compounds can’t dissolve in water?

Answer 3

It turns out that some ionic compounds do not dissolve in water
An insoluble ionic compound product is called a precipitate

Question 4

If theres no percipitates formed?

Answer 4

No Precipitate = No Reaction!

Two aqueous ionic compounds will only undergo a double displacement reaction if ONE of the products is a precipitate

Question 5

How do we know if a precipitate forms??

Answer 5

We use the Solubility Table!

Question 6

Double Displacement Reactions that Produce a Gas

Direct gas production:

Answer 6

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!

Question 7

Double Displacement Reactions that Produce a Gas

Hydrides

Answer 7

LiH (s) + H2O (l) 🡪 LiOH (aq) + H2 (g)
Hydrides react readily with water to produce hydrogen gas
Remember: treat water as H+OH-

Question 8

Indirect gas production:
H2CO3(aq)

Answer 8

unstable!
Will break down into H2O (l) + CO2 (g)

Question 9

Indirect gas production H2SO3 (aq)

Answer 9

Unstable!
Makes H2O (l) + SO2 (g)

Question 10

Indirect gas production: NH4OH (aq)

Answer 10

Unstable!
Produces NH3 (g) + H2O (l)

Question 11

Summary of Gas-Producing Double Displacement Reactions

Sulfides (e.g. Na2S) + Acid

Answer 11

Hydrogen sulfide, H2S

Remember, the reactants listed above must react with an ACID to produce the gas listed!

Question 12

Summary of Gas-Producing Double Displacement Reactions

Carbonates (e.g. Na2CO3) + Acid

Answer 12

Carbon dioxide, CO2

Remember, the reactants listed above must react with an ACID to produce the gas listed!

Question 13

Summary of Gas-Producing Double Displacement Reactions

Sulfites (e.g. K2SO3) + Acid

Answer 13

Sulfur dioxide, SO2

Remember, the reactants listed above must react with an ACID to produce the gas listed!

Question 14

Summary of Gas-Producing Double Displacement Reactions

Hydride (e.g. LiH) + water

Answer 14

Hydrogen gas, H2

Question 15

Summary of Gas-Producing Double Displacement Reactions

Ammonium salt (e.g. NH4Cl) + base

Answer 15

Ammonia, NH3

Question 16

Neutralization

Answer 16

The H+ and Na+ switch places, so this is a double displacement reaction!
But…the reactants are an acid (HCl) and a base (NaOH), so it gets a special name: neutralization

Question 17

Neutralization with a Carbonate

Answer 17

Carbonates react with acids to produce carbonic acid, H2CO3(aq), which (as you know) is unstable!
Makes H2O and CO2

Question 18

NaHCO3 – An unusual carbonate!

Answer 18

NaHCO3 can neutralize an acid!
NaHCO3 can also neutralize a base!

Question 19

Reaction Conditions

Answer 19

Catalysts, heat, pressure, electricity, etc
Are NOT reactants!
Help to speed up a reaction
Often written above the reaction arrow