Types of Chemical Reactions

Question 1

Precipitation Reactions

Answer 1

Definition: A reaction where two aqueous ionic compounds react to form an insoluble solid (precipitate).

General Form: AB(aq)+CD(aq)→AD(s)+CB(aq)

How to Identify:
- Reactants are two aqueous ionic compounds.
- A solid (precipitate) forms based on solubility rules.

Ex: Na2​SO4​(aq)+BaCl2​(aq)→2NaCl(aq)+BaSO4​(s)

Question 2

Acid-Base (Neutralization) Reactions

Answer 2

Definition: A reaction where an acid donates H⁺ to a base, forming water and a salt.

General Form: Acid+Base→Salt+Water

How to Identify:
- Reactants include an acid (H⁺ donor) and a base (OH⁻ donor).
- Products are water (H₂O) and a salt.

Example: HCl(aq)+NaOH(aq)→NaCl(aq)+H2O(l)

Question 3

Oxidation-Reduction (Redox) Reactions

Answer 3

Definition: A reaction where electrons are transferred, changing oxidation states.

Oxidation: Loss of electrons → oxidation number increases
Reduction: Gain of electrons → oxidation number decreases

General Form: A+B → A+ + B-

How to Identify:
- Look for changes in oxidation numbers of elements.
- Involves transfer of electrons.

Example: Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)

Question 4

Double Replacement Reactions

Answer 4

Definition: A reaction where two ionic compounds exchange partners to form new compounds.

General Form: AB + CD → AD + CB

How to Identify:
- Reactants are two ionic compounds.
- Usually forms a precipitate, gas, or water.
- In this the SOLID is the precipitate
Ex: AgNO3​(aq) + NaCl(aq) → AgCl(s) + NaNO3​(aq)

Question 5

Single Replacement Reactions

Answer 5

Definition: A reaction where one element replaces another in a compound.

General Form: A+BC→AC+B

How to Identify:
- Reactants are an element and a compound.
- One element replaces another based on reactivity.

Example: Fe(𝑠) + CuSO4(𝑎𝑞) → FeSO4(𝑎𝑞) + Cu(𝑠)

Question 6

Combination (Synthesis) Reactions

Answer 6

Definition: A reaction where two or more reactants combine to form a single product.

General Form: A+B→AB

How to Identify:
- One product forms from multiple reactants
Example: 2H2(𝑔) + O2(𝑔) → 2H2O(𝑙)

Question 7

Decomposition Reactions

Answer 7

Definition: A reaction where one compound breaks down into two or more products.

General Form: AB→A+B

How to Identify:
- One reactant splits into multiple products.

Example: 2H2O2(𝑙) → 2H2O(𝑙) + O2(𝑔)

Question 8

Combustion Reactions

Answer 8

Definition: A reaction where a fuel (usually hydrocarbon) reacts with oxygen to produce CO₂ and H₂O.

General Form: Fuel+O2​→CO2​+H2​O

How to Identify:
- Oxygen (O₂) is a reactant.
- CO₂ and H₂O are products.

Example: CH4(𝑔) + 2O2(𝑔) → CO2(𝑔) + 2H2O(𝑔)