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2023 WAEC Chemistry Theory a. Describe how iron and aluminum reacts with each of the following substances: i.  dilute \(H_2SO_4\);...

Chemistry
WAEC 2023

a. Describe how iron and aluminum reacts with each of the following substances: i.  dilute \(H_2SO_4\); ii.   dilute \(HNO_3\)

bi. Write an equation for the burning of sulphur in air.

ii. Name the catalyst used in the contact process.

iii. In the contact process, why is an excess of air used?

iv. Why is it necessary to cool the catalyst used in 5(b)(ii)?

v. Give a reason why the air used in the contact process needs to be as clean as possible.

vi. State two reasons why SO2 should not be discharged into the atmosphere.

ci. State the reagents and conditions used in the laboratory preparation of chlorine.

ii. State two uses of chlorine.

di. Name the drying agents for each of the following gases: 1. Hydrogen; 

i2.  sulphur (IV) oxide; 

i3. Ammonia.

ii1. State the components of the following
      Bronze;  ii2. Brass.


 

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Explanation

ai. Iron dissolves readily in dilute \(H_2SO_4\) liberating hydrogen and forming \(FeSO_4\) while with Aluminum there is no reaction.

 

ii. With aluminum there is no reaction(1)while iron dissolves in dilute \(HNO_3\) liberating hydrogen and forming \(Fe(NO_3)_2\)

 

bi. \(S+O_2→SO_2\)

 

ii. Vanadium(V) oxide/ platinized asbestos.

 

iii. To favour the formation of more product/\(SO_3\).

 

iv. The reaction is exothermic/high temperature favours the formation of more reactants/backward reaction.

 

v. Catalysts are easily poisoned/easily damaged by dirt.

 

vi. -SO2 damages buildings
     -damages living things
     -causes acid rain
     -irritates eyes, nose and throat
     -causes lung and respiratory diseases eg coughing, bronchitis, etc

 

ci. Reagents
    -manganese(IV)oxide/MnO2
     -concentrated HCI

      Conditions
     -heating
     Concentrated HCI(1)
     Bleaching powder/CaOCl2/KMnO4crystals
     Room temperature/heat is not required

 

ii. 

-for bleaching wood pulp and textiles
-for the production of plastics
-for recovering of tin from its ore/extraction of tin
-as a germicide and disinfectant/insecticide/in swimming pools
-to sterilize/purification of water supply
-for commercial manufacture of HCI
-production of dyes and drugs
-manufacture of solvents eg \(CCL_4\), \(CHCI_3\)

 

di1. Hydrogen-fused calcium chloride/conc.tetraoxosulphate(VI)acid

 

i2. Sulphur(IV)oxide-concentrated tetraoxosulphate(VI)acid/ anhydrous Calcium chloride

 

i3. calcium oxide/ quick lime/silica gel

 

ii1. copper  and  tin

 

ii2. Copper and zinc


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WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
WAEC offline past questions - with all answers and explanations in one app - Download for free
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
WAEC offline past questions - with all answers and explanations in one app - Download for free