Q7. (a) The following question is pertaining to the laboratory preparation of hydrogen chloride gas:
(i) Write the equation for its preparation mentioning the condition required.
(ii) Name the drying agent used and justify your choice.
(iii) State a safety precaution you would take during the preparation of hydrochloric acid.
i) NaCl +H2SO4(conc.) --> NaHSO4 +HCl
ii) The drying agent is concentrated sulphuric acid because it is an acidic drying agent and other drying agents react with HCl.
iii) The temperature should be raised above 2000C during the preparation of hydrochloric acid because above this temperature it forms sticky substance sodium sulphate that sticks to glass apparatus which becomes difficult to remove and also cause wastage of heat.
Given balanced chemical equation for each of the following:
Lab preparation of ammonia using an ammonium salt.
Explain why:
(1) In the electrolysis of alumina using the Hall Heroult’s process the electrolyte.
(2) Iron sheets are coated with zinc during galvanization.
Identify the acid which matches the following description:
The acid which is used in the preparation of a non-volatile acid.
For each of the substance listed below. Describe the role played in the extraction of aluminium.
(1) Cryolite:
(2) sodium hydroxide
(3) Graphite
Q.1 (b) Choose the most appropriate answer for the following:
(iii) This is not an alloy:
A) brass
B) bronze
C) solder
D) Duralumin
State one relevant observation for the following:
when ammonia gas is burnt in an atmosphere of excess oxygen.
Give appropriate scientific reason for the following statement:
Zinc oxide is reduced to zinc by using carbon monoxide, but aluminium oxide cannot be reduced by a reducing agent.
The acid on mixing with silver nitrate solution produces a white precipitate which is soluble in excess ammonium hydroxide ?
