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2015 WAEC Chemistry Theory (a) Define esterification. (b) State two properties of plastic. (c) Name the components of duralumin....

Chemistry
WAEC 2015

(a) Define esterification.

(b) State two properties of plastic.

(c) Name the components of duralumin.

(d) What is meant by each of the following terms?

(i) Raw material.

(ii) Primary product.

(e) State Charles' law.

(f) List four pieces of protective equipment in the laboratory.

(g) Give two uses of ammonia.

(h) Name the:

(i) process by which lighter hydrocarbons are obtained from heavier ones;

(ii) products formed from the reaction between ethanol and sodium metal.

(i) Determine the oxidation number of sulphur in H\(_2\)SO\(_4\).

(j) Write the IUPAC name for each of the following compounds: (i) NaClO\(_3\); (ii) CuSO\(_4\)5H\(_2\)O.

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Explanation

(a) Define esterification: Esterification is the reaction between an alkanol and alkanoic/organic acid to produce an alkanoate/ester and water in the presence of mineral acid.

 

(b) Properties ottitastic: —Good insulators to heat and electricity. —Can be recycled. —Are non-biodegradable. —Are durable.— can be tailor-made (to suit particular purpose). —Are resistant to corrosion/chemicals. —Can be remoulded.

 

(c) Components of duralumin: —Aluminium, —Magnesium. —Copper. —Manganese.

 

(d)(i) What is meant by raw material: Raw material is a starting material used in producing or manufacturing a substance/product.

(ii) What is meant by primary product: This is the main product of the industry/an intermediate product that can be still converted to other usable product.

 

(e) Charles' law: It states that the volume of a given mass of gas is directly proportional to its absolute temperature/ temperature in Kelvin if the pressure is constant.

 

(f) Protective equipment in the laboratory: —Safety goggle. —Hand gloves. —Laboratory coat/apron. —Boots or safety boot. —Nose mask/shield. —Fume cupboard. --Respirator/ gas mask. —Fire extinguisher.

 

(g) Uses of Ammonia: —As a refrigerant. —For electing aluminium. —As agent for manufacturing of fertilizer. —As solvent for removal of grease and oil stains. —For softening of temporarily hard water. —Use in making/manufacturing ammonium salt. —For treating insect bite. —As agent for manufacturing of HNO\(_3\). —As a precipitating agent for qualitative analysis.

 

(h)(i) Process by which lighter hydrocarbons are obtained from heavier ones: —Cracking.

(ii) Products:formed from the reaction between ethanol and sodium metal: —Sodium ethoxide + Hydrogen gas.

(iii) Oxidation number of sulphur in H\(_2\)SO\(_4\)

H\(_2\)SO\(_4\) = 2 x 1 + 5 + 4(-2) — 2 = 0

= 2 + 5 — 8 = 0

2 + 5 = 8

5 = 8 — 2 = 6

5 = 6

 

(j) IUPAC name of: (i) NaClO\(_3\) —>Soludium trioxochlorate(V).

(ii) CUSO\(_4\)SH\(_2\)O —> Copper (II) tetraoxosulphate (VI) —> -pentahydrate
 


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WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
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