Alkenes and Bromine Water
IGCSE Edexcel Chemistry
4.23-4.28 Alkenes and tests
Key Concept:
Alkenes have a C=C bond and decolorize bromine water by addition.
Section A: Alkenes
1. State the general formula for alkenes.
[1]
2. Explain why alkenes are unsaturated.
[2]
3. Draw the displayed formula for ethene (C2H4).
[2]
Section B: Bromine Water
4. Describe the test for alkenes using bromine water and the positive result.
[2]
5. Write the word equation for ethene reacting with bromine.
[2]
Total marks: 9
Mark Scheme
1.
CnH2n [1]
2.
Contains a carbon-carbon double bond; can add atoms to it [2]
3.
H2C=CH2 with correct bonds [2]
4.
Add bromine water; orange/brown to colorless [2]
5.
Ethene + bromine -> dibromoethane [2]