Bab 8 1

The experimental set-up for the anodisation of aluminium is shown. Set up apparatus for electrolysis, battery, electrode Aluminium & Carbon, electeolite dilute sulphuric acid. The purpose of the process is to...

• form a thicker oxide layer on aluminium
• purify aluminium
• polish the surface of aluminium
• increase the mass of aluminium

Which statement explains why graphite powder is spread onto plastic material first in plastic electroplating process?

• graphite is an electric conductor
• plastic becomes more resistant to heat
• plastic electroplating process is accelerated
• graphite can form chemical bond with plastic

Aluminium is obtained on a large scale by a recycling process. Which is not the advantage of the process in comparison with electrolysis of bauxite?

• the density of aluminium is lower than that of bauxite
• less costly
• easier to carry out
• enables conservation of natural resources

Aluminium in dust form could be used as rocket fuel. It is obtained from pure bauxite by electrolysis. Which statement is not true about the process?

• the molten aluminium floats at the surface of the electrolysis container
• carbon dioxide gas is released at the anode
• the ions in the electrolyte are Na+, Al3+, O2- and AlF6 3-
• bauxite solution in cryolite is a good electric conductor

Iron is protected from corrosion when in contact with aluminium but it corrodes more rapidly when contact with tin. Why?

• Aluminium is a stronger reducing agent than iron
• Tin is a stronger reducing agent than iron

By write the electronic configuration of Fe2+ and Fe3+ ions. Which one is more stable between Fe2+ and Fe3+ ions?

• Fe3+ ion is more stable because of the 3d subshell is half-filled
• Fe2+ ion is more stable because of the 3d subshell is half-filled
• Fe3+ ion is more stable because occupied by two electrons that electrostatic repulsion
• Fe2+ ion is more stable because occupied by two electrons that electrostatic repulsion