Show how to draw Lewis dot structures for the balanced reaction of the combustion of methane (CH4). Show how to draw the Lewis dot structures for the balanced reaction of the combustion of ethanol (C2H5OH). Show how to draw Lewis dot structures for the balanced reaction of the combustion of hydrogen (H2).
The Correct Answer and Explanation is:
Lewis Dot Structures for Combustion Reactions
1. Combustion of Methane (CH₄)
Balanced equation:
CH₄ + 2O₂ → CO₂ + 2H₂O
Lewis Structures:
- CH₄ (Methane):
Carbon is in the center with 4 hydrogen atoms single bonded around it. markdownCopyEditH | H - C - H | H - O₂ (Oxygen gas):
Each O shares two electrons (double bond) iniCopyEditO = O - CO₂ (Carbon dioxide):
Carbon is double bonded to each oxygen atom mathematicaCopyEditO = C = O - H₂O (Water):
Oxygen in center with 2 single bonds to hydrogen, and two lone pairs on O markdownCopyEditH - O - H .. ..
2. Combustion of Ethanol (C₂H₅OH)
Balanced equation:
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
Lewis Structures:
- C₂H₅OH (Ethanol):
CH₃−CH₂−OH, carbon atoms bonded to H and OH mathematicaCopyEditH H H H | | | | H - C - C - O - H | H - O₂: iniCopyEdit
O = O - CO₂: mathematicaCopyEdit
O = C = O - H₂O: markdownCopyEdit
H - O - H .. ..
3. Combustion of Hydrogen (H₂)
Balanced equation:
2H₂ + O₂ → 2H₂O
Lewis Structures:
- H₂ (Hydrogen gas): nginxCopyEdit
H − H - O₂ (Oxygen gas): iniCopyEdit
O = O - H₂O (Water): markdownCopyEdit
H - O - H .. ..
Explanation (300 words)
Lewis dot structures represent the valence electrons in molecules and help visualize how atoms bond during chemical reactions. In combustion reactions, a hydrocarbon (or hydrogen gas) reacts with oxygen gas to form carbon dioxide and water. Each atom must follow the octet rule (or duet for hydrogen), meaning it should achieve a full outer shell through bonding.
In the combustion of methane (CH₄), the carbon atom forms four single bonds with hydrogen atoms. Oxygen gas (O₂) consists of two oxygen atoms sharing a double bond. In the reaction, CH₄ and O₂ rearrange to form CO₂ and H₂O. Carbon in CO₂ forms two double bonds with oxygen, fulfilling the octet rule. Water has two single bonds between oxygen and hydrogen, and oxygen retains two lone pairs.
In ethanol (C₂H₅OH), the molecule includes a hydroxyl group (OH) bonded to a carbon chain. Each carbon obeys the octet rule, and each hydrogen has a single bond. During combustion, the ethanol reacts with three oxygen molecules to yield two carbon dioxide molecules and three water molecules. The electrons rearrange such that carbon atoms form double bonds with oxygen in CO₂, and oxygen in water maintains its two lone pairs.
Hydrogen gas (H₂) is a simple diatomic molecule with a single bond between two hydrogen atoms. Oxygen again exists as a diatomic molecule with a double bond. When H₂ combusts, it reacts with O₂ to produce H₂O. Each water molecule contains two hydrogen atoms bonded to one oxygen atom, which also has two lone pairs.
These Lewis structures help us visualize electron movement and confirm that each atom satisfies bonding rules. They provide essential insight into how atoms rearrange during chemical reactions.
