Expert Chemistry & Science Tutoring

• Introduction:

Key Concepts and Definitions:

• Alkanes:
• Saturated hydrocarbons containing only single CC bonds
• General formula: CnH2n+2
• Common example: Methane (CH4)
• Alkenes:
• Unsaturated hydrocarbons with at least one C=C double bond
• General formula: CnH2n
• Common example: Ethene (C2H4)

Chemical Equations and Reactions:

• Combustion:
• Alkanes and alkenes react with oxygen to release heat and light energy.
• Example: CH4 + 2O2 → CO2 + 2H2O
• Addition Reactions (Alkenes only):
• Alkenes react with compounds containing double or triple bonds to add to the C=C bond.
• Example: C2H4 + H2 → C2H6

Step-by-Step Explanations:

• Identifying Alkanes and Alkenes:
• Check the CC bonds: Single CC bonds for alkanes, double CC bonds for alkenes
• Count the number of H atoms: Use the formulas to determine if the molecule is saturated (alkanes) or unsaturated (alkenes)
• Exam Tips:
• Understand the key differences between alkanes and alkenes
• Practice writing combustion equations and addition reactions
• Use examstyle questions to test your knowledge

Common Mistakes to Avoid:

• Confusing alkanes and alkenes due to similar names
• Not balancing equations correctly
• Not understanding the addition reactions of alkenes

Practice Problems (with Solutions):

1. Write the combustion equation for propane (C3H8).

Solution: C3H8 + 5O2 → 3CO2 + 4H2O

2. Identify whether the following molecule is an alkane or alkene: C3H6

Solution: Alkene (contains a C=C bond)

Conclusion:

Alkanes and alkenes are essential concepts for GCSE Chemistry. Understanding their properties, reactions, and exam tips will help you achieve success in your science exams.

FAQs:

• Why are alkanes called saturated hydrocarbons? They contain the maximum number of hydrogen atoms possible.
• Can alkenes undergo combustion reactions? Yes, but they also undergo addition reactions with unsaturated compounds.
• What is an example of an industrial use of alkanes? Butane is used as a fuel in cigarette lighters.