Application of Electrolysis

Chlorine is produced from the electrolysis of sodium chloride solution in a diaphragm cell. What is the use of the diaphragm in the cell

• Removes impurities from sodium chloride

• Increases the rate of production of chlorine

• Prevents chlorine from escaping from the cell

• Prevents chlorine from coming into contact with sodium hydroxide

What is the advantage of producing sodium hydroxide using a mercury cell?

• The voltage required for the elctrolysis is lower

• The sodium hydroxide formed has a higher purity

• The by products are environmentally friendly

• The process is more economical

Which of the following statements is NOT true about the rusting of an iron nail

• Corrosion is the oxidation deterioration of a metal by an electrochemical process

• Iron rusts faster if it is in contact with a more electropositive metals

• Rusting of iron occurs when oxygen and water are present

• When iron rusts, iron is first oxidised to Fe²⁺ ions

What is frequently done to protect aluminium articles from subsequent corrosion?

• Aluminium is coated with an inert metal

• Cryolite is added to the aluminium ore before it is used

• Aluminium is first oxidised by air to form an inert oxide layer

• The aluminium is made the anode during electrolysis

Industrially, aluminium is extracted from the electrolysis of its molten ore. However, why is more emphasis placed on recycling of aluminium than the extraction of aluminium from its ore?

• The extraction process is very difficult

• The cost of extracting aluminium from its ore is very high

• Extracting aluminium from its ore will contaminate the environment

• Extracting aluminium from its ore will cause the source to be depleted

One of the alloys used in a dental filling is Ag₃Sn. The standard reduction potentials of Al³⁺(aq)/Al(s) and Sn²⁺(aq)/Ag₃Sn(s) half cells are -1.66V and -0.05V respectively. Which of the following statements is NOT true when a piece of aluminium comes into contact with the dental filling?

• The e.m.f. of the electrochemical cell created is +1.61V

• The electrons flow from the dental filling to aluminium

• Aluminium acts as the anode

• Al³⁺ ions are produced

A large number of objects such as bathroom accessories, are metal-plated plastics. Which of the following is NOT the advantage of used metal-plated plastic objects over a metal object?

• More durable

• Less expensive

• Lighter

• More resistant to corrosion

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

Which of the following pairs of substances is used in the industrial production of chlorine by electrolysis?

• Carbon anode and dilute sodium chloride

• Carbon anode and concentrated sodium chloride

• Platinum anode and dilute sodium chloride

• Platinum anode and molten sodium chloride

All of the following are advantages of using a hydrogen-oxygen fuel cell in an electric car except

• lighter

• smaller size

• higher voltage

• cheaper