With the aid of schematic diagrams and an hypothetical chemical reactions, differentiate with three examples each, Exothermic reaction and Endothermic reactions?

Exothermic reactions:

1. Combustion of methane:
In this reaction, methane (CH4) reacts with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O) along with the release of heat energy.
CH4 + 2O2 -> CO2 + 2H2O + heat

2. Neutralization of hydrochloric acid and sodium hydroxide:
When hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), it forms sodium chloride (NaCl) and water (H2O) with the release of heat.
HCl + NaOH -> NaCl + H2O + heat

3. Rusting of iron:
When iron (Fe) reacts with oxygen (O2) and water (H2O), it forms iron oxide (Fe2O3) along with the release of heat energy.
4Fe + 3O2 + 6H2O -> 2Fe2O3 + heat

Endothermic reactions:

1. Photosynthesis:
In this reaction, carbon dioxide (CO2) and water (H2O) react in the presence of sunlight to produce glucose (C6H12O6) and oxygen (O2) with the absorption of energy.
6CO2 + 6H2O + energy -> C6H12O6 + 6O2

2. Dissolution of ammonium nitrate in water:
When ammonium nitrate (NH4NO3) dissolves in water, it absorbs heat from the surroundings, causing the solution to become cold.
NH4NO3 + H2O + energy -> NH4+ + NO3- + H2O

3. Melting of ice:
When ice (H2O) is heated, it absorbs heat energy to break the hydrogen bonds holding the water molecules together, resulting in the phase change from solid to liquid.
H2O (s) + energy -> H2O (l)

Exothermic Reactions

An exothermic reaction is a chemical reaction that releases energy in the form of heat. This means that the products of the reaction have less energy than the reactants. The change in energy between the reactants and products is negative.

Examples:

1. Combustion of methane:

```
CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l) + heat
```

In this reaction, methane and oxygen react to form carbon dioxide and water. The products have less energy than the reactants, so the reaction releases heat.

2. Neutralization of an acid and base:

```
HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l) + heat
```

In this reaction, hydrochloric acid and sodium hydroxide react to form sodium chloride and water. The products have less energy than the reactants, so the reaction releases heat.

3. Condensation of water:

```
H₂O(g) → H₂O(l) + heat
```

In this reaction, water vapor condenses to form liquid water. The liquid water has less energy than the water vapor, so the reaction releases heat.

Endothermic Reactions

An endothermic reaction is a chemical reaction that absorbs energy in the form of heat. This means that the products of the reaction have more energy than the reactants. The change in energy between the reactants and products is positive.

Examples:

1. Decomposition of water:

```
2H₂O(l) → 2H₂(g) + O₂(g) - heat
```

In this reaction, water decomposes to form hydrogen and oxygen. The products have more energy than the reactants, so the reaction absorbs heat.

2. Melting of ice:

```
H₂O(s) → H₂O(l) - heat
```

In this reaction, ice melts to form liquid water. The liquid water has more energy than the ice, so the reaction absorbs heat.

3. Evaporation of water:

```
H₂O(l) → H₂O(g) - heat
```

In this reaction, liquid water evaporates to form water vapor. The water vapor has more energy than the liquid water, so the reaction absorbs heat.