COMBINATION REACTION...

H2 + O2------------->H2O
SO3 + H2O-------->H2SO4
Fe + S----------------> FeS
N2 + 3H2-----------> NH3
NH3 + HCl--------->NH4Cl



DOUBLE DISPLACEMENT REACTION.

2NaOH + (NH4)2SO4------->. 2NH4OH + Na2SO4
Pb(NO3)2 + H2SO4--------> PbSO4 + HNO3
BaCl2 + Na2SO4---------> BaSO4 + 2NaCl
PbNO3 + 2KI--------> 2KNO3 + PbI2
NaHCaO3+ CH3COOH-------> H2CO3 + NaCH2

Combination Reactions:

Combination reactions, also known as synthesis reactions, occur when two or more substances combine to form a single compound. This type of reaction is characterized by the absence of any products other than the compound formed. Here are five examples of combination reactions:

1. Formation of water (H2O):
- The combination of hydrogen gas (H2) and oxygen gas (O2) results in the formation of water.
- The balanced chemical equation for this reaction is: 2H2 + O2 → 2H2O.
- This reaction is a crucial part of the water cycle and is commonly known as combustion.

2. Formation of magnesium oxide (MgO):
- When magnesium metal (Mg) reacts with oxygen gas (O2), magnesium oxide is formed.
- The balanced chemical equation for this reaction is: 2Mg + O2 → 2MgO.
- This reaction is often used to study the reactivity of metals with oxygen.

3. Formation of calcium carbonate (CaCO3):
- When calcium oxide (CaO) reacts with carbon dioxide (CO2), calcium carbonate is produced.
- The balanced chemical equation for this reaction is: CaO + CO2 → CaCO3.
- This reaction is important in the formation of limestone and in the carbon cycle.

4. Formation of iron(III) oxide (Fe2O3):
- The reaction between iron metal (Fe) and oxygen gas (O2) leads to the formation of iron(III) oxide.
- The balanced chemical equation for this reaction is: 4Fe + 3O2 → 2Fe2O3.
- This reaction is commonly known as rusting and is responsible for the degradation of iron objects in the presence of moisture.

5. Formation of ammonia (NH3):
- The combination of nitrogen gas (N2) and hydrogen gas (H2) results in the formation of ammonia.
- The balanced chemical equation for this reaction is: N2 + 3H2 → 2NH3.
- This reaction is of great industrial importance as ammonia is widely used in the production of fertilizers and other chemicals.

Double Displacement Reactions:

Double displacement reactions, also known as double replacement reactions or metathesis reactions, occur when the cations and anions of two compounds exchange places to form new compounds. Here are five examples of double displacement reactions:

1. Formation of sodium chloride (NaCl):
- When sodium hydroxide (NaOH) reacts with hydrochloric acid (HCl), sodium chloride is formed.
- The balanced chemical equation for this reaction is: NaOH + HCl → NaCl + H2O.
- This reaction is a classic example of neutralization and is commonly used in the laboratory to prepare common salt.

2. Formation of silver chloride (AgCl):
- When silver nitrate (AgNO3) reacts with sodium chloride (NaCl), silver chloride is formed.
- The balanced chemical equation for this reaction is: AgNO3 + NaCl → AgCl + NaNO3.
- This reaction is often used in qualitative analysis to detect the presence of chloride ions.

3. Formation of lead(II) iodide (PbI2):
- The reaction between lead(II) nitrate (Pb(NO3)2)