Carmel (2015)

Question 1

Explain why cobalt is malleable and ductile in regard to its bonding. (2)

Answer 1

• Cobalt has metallic bonding, which is characterised by non-directional bonding between the delocalised sea of electrons and the positive metal ions.
• This accounts for its malleability and ductility, as when struck, bonding isn’t disrupted.

Question 2

What is an allotrope? (1)

Answer 2

• Different structural arrangement of the same element

Question 3

Explain how the Law of Conservation of Energy applies to exothermic reactions. (2)

Answer 3

• Negative change in enthalpy shows products have less chemical PE than reactants.
• Energy has not been lost but rather converted (to KE) and released as heat, ensuring the total amount of energy in system is the same and Law is conserved.

Question 4

Describe the composition of petrol. (2)

Answer 4

*Mixture of hydrocarbons
*Typically, 4-12 carbons in their structure