W5 August CS-S4A Chem Prelim Revision 7: Organic Chem

Margarine is often described as ‘rich in polyunsaturated fats’. What can we infer from this statement?

• long chain alkane molecules

• many alkene molecules joined together by addition polymerisation

• molecules containing many C=C bonds

• molecules containing hydrogen and carbon only

Two hydrocarbon molecules X and Y each contain only four carbon atoms. X is saturated while Y is unsaturated. Which of the following statements are correct? Select all options that apply.

• Both X and Y contain only carbon and hydrogen atoms.

• Complete combustion of 1 mole of X produces more carbon dioxide than the complete combustion of 1 mole of Y.

• One molecule of Y contains more hydrogen atoms than one molecule of X.

• Under suitable conditions, Y polymerises.

20 cm³ of ethene is reacted with 30 cm³ of hydrogen to form ethane gas. What is the total volume of gas at the end of the reaction?

• 20 cm³

• 30 cm³

• 50 cm³

• 70 cm³

When 1 mole of C₁₁H₂₄ is cracked, only 3 compounds are formed: ethene, propene and propane.

What is the number of moles of each compound formed?

• A

• B

• C

• D

Ethanol can be made via fermentation in a laboratory at room temperature. State what temperature this reaction should be carried out at, and explain why the temperature of the reactants must not be allowed to rise above that temperature.