Given below is a list of chemical reactions. 1. burning octane fuel 2. forming rust in an iron pipe 3. baking a cake 4. cement hardening which sequence ranks the chemical reactions in order from fastest to slowest?

Answer is: 1, 3, 4, 2.

1) Burning octane fuel is very fast chemical reaction, it happens in immediately.

Main products of the combustion of fossil fuels are carbon(IV) oxide and water.

Chemical reaction: C₈H₁₈ + 25/2O₂ → 8CO₂ + 9H₂O; ΔH = -5500 kJ/mol.

2) Baking cake usually last for 30-60 minutes.

3) Cement hardening last for few days.

4) Forming rust usually last for few months.

Balanced chemical reaction of forming rust: 4Fe + 3O₂ → 2Fe₂O₃.