1. Single Replacement & Double Replacement
Unit 6 – Lesson 3
Single Replacement & Double Replacement

2. A + BC  AC + B 4. Single Replacement (SR)
A single element and a compound become a different element and a different compound.
A + BC  AC + B

3. In this class, the most common SR will be a metal-metal replacement
Most reactive
Least reactive
In this class, the most common SR will be a metal-metal replacement
If the metal that is single is more reactive than the one in the compound, the metals will switch places
Use the activity series to determine reactivity of the metals
Fe(s) + CuSO4 (aq)
Cu(s) + FeSO4(aq)
video

4. 2 AgNO3(aq) + Cu(s)  2 Ag(s) + Cu(NO3)2(aq)
Most reactive
Least reactive
Cu(s) + AgNO3(aq) 
Ag(s) + Cu(NO3)2(aq)
2 AgNO3(aq) + Cu(s)  2 Ag(s) + Cu(NO3)2(aq)

5. Complete & Balance
Mg (s) + NaBr(aq) 
no rxn (reaction)
AgNO3(aq) + Mg(s) 
Ag(s) + Mg(NO3)2(aq)
2 AgNO3(aq) + Mg(s)  2 Ag(s) + Mg(NO3)2(aq)
FeI3(aq) + K(s) 
KI(aq) + Fe(s)
FeI3(aq) + 3 K(s)  3 KI(aq) + Fe(s)

6. * Notice it matches the positions from the periodic table!
Another example of SR would be a halide-halide replacement
Halide = Halogen
If the halogen that is single is more reactive than the one in the compound, the halogens will switch places
Most reactive
Least reactive
Use the activity series to determine reactivity of the halides
* Notice it matches the positions from the periodic table!
F2 + CaCl2 
Cl2 + CaF2
Br2 + MgCl2 
no rxn (reaction)
Cl2 + CaI2 
I2 + CaCl2

7. AB + CD  AD + CB 5. Double Replacement (DR)
When the cations in two compounds switch places/partners.
AB + CD  AD + CB

8. In aqueous solutions, the dissolved compound is broken into ions
Typically occurs between two ionic compounds in aqueous solutions.
In aqueous solutions, the dissolved compound is broken into ions

9. **If both products are aqueous the reaction will NOT occur**
A reaction will ONLY occur if one of the possible products is either a…
a. precipitate (solid)
AgNO3(aq) + NaCl(aq)  AgCl(s) + NaNO3(aq)
A precipitate forms when one of the products is insoluble (does not dissolve) in water.
Use the solubility rules in the reference packet to determine if either product is insoluble.
**If both products are aqueous the reaction will NOT occur**

10. How to READ the Solubility Rules
Look up the anion (second part) of the compound
AgNO3
Ba(OH)2
MgCO3
MgF2
If the anion is on the soluble side it will be aqueous UNLESS it is an exception
If the anion is on the insoluble side it will be solid UNLESS it is an exception
AgNO3 -
aqueous
MgCO3 -
solid
Ba(OH)2 -
aqueous
MgF2 -
solid

11. Predict the possible products to determine if the reaction will occur.
**If both products are aqueous the reaction will NOT occur**
BaCl2(aq) + KNO3(aq) 
Ba(NO3)2
(aq)
+ KCl
(aq)
NO RXN
YES!
FeCl3 (aq) + Na3PO4 (aq) 
NaCl
(aq)
+ FePO4
(s)
FeCl3 (aq) + Na3PO4 (aq)  3 NaCl (aq) + FePO4 (s)
NO RXN
AgF (aq) + KNO3 (aq) 
AgNO3
(aq)
+ KF
(aq)
AgNO3 (aq) + NaCl (aq) 
NaNO3
(aq)
+ AgCl
(s)
YES!
AgNO3 (aq) + NaCl (aq)  NaNO3 (aq) + AgCl (s)

12. b. water
Ex. Acid-base neutralization
HCl (aq) + NaOH (aq)  NaCl (aq) + H2O (l)
HNO3(aq) + NaOH(aq)  NaNO3(aq) + H2O (l)
c. gas
HCl (aq) + NaHCO3 (aq)  NaCl (aq) + CO2 (g) + H2O (l)
For a double replacement reaction to occur one product has to be a solid, gas or H2O.

13. Testing for Common Products
Oxygen: A glowing splint will burst into flame in pure oxygen.
Hydrogen: A lighted splint inserted into an inverted test tube full of Hydrogen (H2 is lighter than air hence the inverted tube), will produce a 'squeaky' 'POP'! as it ignites.
CO2: CO2 will turn lime water cloudy. Also, a test tube full of CO2 (not inverted as it's heavier than air) will extinguish a burning splint inserted into it.
The standard test for water is to use cobalt (II) chloride paper. This is paper soaked in cobalt(II) chloride (CoCl2) solution. It turns from blue to pink upon exposure to water.