(a)(i) Draw and label a diagram to illustrate the preparation and collection of dry chlorine gas in the laboratory. (ii) State two uses of chlorine. (b) Des...

(a)(i)   Draw and label a diagram to illustrate the preparation and collection of dry chlorine gas in the laboratory.
(ii)  State two uses of chlorine.
 

(b) Describe the preparation of hydrogen from water gas.

(i)   Name the chief ore of aluminium.

(ii)  Why is the ore purified?
(iii)  Name the electrode used in the electrolysis.
(iv)  Give one reason why cryolite, NaAlF\(_6\), is added to the electrolyte.
 

(c) Name three products obtained directly from the destructive distillation of coal.                                       

Answer Details

(a) (i) To prepare and collect dry chlorine gas in the laboratory, a setup as shown in the diagram below can be used:

In the diagram, a container of hydrochloric acid (HCl) is connected to a gas delivery tube which is placed over a container of calcium hydroxide (Ca(OH)2) through a delivery tube. The hydrochloric acid and calcium hydroxide react to produce chlorine gas, which is collected in the container over the calcium hydroxide. The container is sealed so that the chlorine gas does not escape.

(ii) Two uses of chlorine are:

1. Disinfection: Chlorine is commonly used as a disinfectant in water treatment to kill bacteria, viruses and other harmful microorganisms.
2. Bleaching: Chlorine is used as a bleach in the paper and textile industry, as well as in the production of many household cleaning products, to remove color and brighten materials.

(b) The preparation of hydrogen from water gas can be carried out by a process called water gas shift reaction. This reaction involves the reaction of carbon monoxide (CO) and steam (H2O) over a catalyst to produce hydrogen (H2) and carbon dioxide (CO2). The reaction can be represented by the equation:

CO + H2O ? H2 + CO2

(i) The chief ore of aluminum is bauxite.

(ii) The ore is purified to remove impurities, such as silica and iron, which would interfere with the electrolysis process used to extract aluminum from the ore.

(iii) The electrode used in the electrolysis is a carbon electrode.

(iv) Cryolite, NaAlF6, is added to the electrolyte to lower the melting point of the electrolyte, allowing the aluminum to be extracted at a lower temperature.

(c) Three products obtained directly from the destructive distillation of coal are:

1. Coal gas: Also known as town gas, this is a mixture of gases including methane, hydrogen, and carbon monoxide that can be used as a fuel.
2. Coal tar: A thick, black liquid that is a byproduct of coal gas production. It can be further processed to produce chemicals such as benzene, toluene, and naphthalene.
3. Coke: A solid, porous material that is used as a fuel and as a reducing agent in the production of iron and steel.