Summarize the processes of rusting prevention, separation of solids, differences between CO and CO2, and aluminium-chlorine reaction.

18. Three differences between carbon (II) oxide ($\text{CO}$) and carbon (IV) oxide ($\text{CO}_2$):

• Carbon (II) oxide ($\text{CO}$) is a neutral oxide, while carbon (IV) oxide ($\text{CO}_2$) is an acidic oxide.
• Carbon (II) oxide ($\text{CO}$) is flammable, while carbon (IV) oxide ($\text{CO}_2$) is non-flammable.
• Carbon (II) oxide ($\text{CO}$) is highly toxic, while carbon (IV) oxide ($\text{CO}_2$) is non-toxic (though high concentrations can be harmful).

19. a) Aluminium reacts with chlorine gas.

$$2\text{Al}(s) + 3\text{Cl}_2(g) \rightarrow 2\text{AlCl}_3(s)$$

b)
The type of bond is ionic.
The structure formed is a giant ionic lattice.

20. Convert the following values from degrees Celsius to Kelvin:

a) $0^\circ\text{C}$
To convert Celsius to Kelvin, add 273.15.

$$0^\circ\text{C} + 273.15 = 273.15\text{ K}$$

The value is $\boxed{\text{273.15 K}}$.