Alkanes

Question 1

Alkanes

Answer 1

General Formula: CnH2n+2
Un/saturated compound: saturated (doesn’t react easily, doesn’t contain a double carbon bond)
C=C: does not contain C=C
Reaction: Substitution reaction
Fuels that burn in oxygen

Question 2

Reaction of Alkanes with Bromine

Answer 2

Reaction: Substitution reaction
Method: 1. Shake bromine with an alkane.
2. Check if bromine remains orange.
3. Put the test tube into sunlight.*

*Bromine decolourises in time. It needs UV for the reaction to happen.

Question 3

Complete Combustion of Alkanes

Answer 3

There is a plentiful supply of oxygen.
Carbon dioxide and water are the products.

Question 4

Word and Symbol Equation

*For the complete combustion of alkanes.

Answer 4

methane + oxygen -> carbon dioxide and water
CH₄ + (4/)2O₂ -> CO₂ + 2H₂O
ethane + oxygen -> carbon dioxide and water
C₂H6 + 7/2O₂ -> 2CO₂ + 3H₂O
Of the products, the amount of CO₂ is equal to the amount of carbons in methane (1). The O₂ is just the amount of CO₂ + 1.

Question 5

Incomplete Combustion of Alkanes

Answer 5

There is an insufficient/ limited supply of oxygen.
The products are carbon monoxide (CO)/ carbon (C) and water.

Question 6

Word and Symbol Equation

*For the incomplete combustion of alkanes.

Answer 6

methane + oxygen -> carbon monoxide and water
CH₄ + 3/2O₂ -> CO + 2H₂O
ethane + oxygen -> carbon dioxide and water
C₂H6 + 5/2O₂ -> 2CO + 3H₂O
Of the products, the amount of CO is equal to the amount of carbons in methane (1). The O₂ is just the amount of CO₂ + 1. Of the O₂ in the reactants, it is the amount of H₂ in the hydrocarbon - 1.