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Chemistry Waec 2015 Expo Runz




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Chemistry 2(Essay) ----- 2.00pm - 4.00pm
Chemistry 1(Obj) ----- 4.00pm - 5.00pm
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CHEM Obj.
1-10 ADCDCCDDDB
11-20 DCABCDBCAA
21-30 BACCBCBDCD
31-40 DBDDBBCCBC
41-50 DCCDCCADAA

(1a)Esterification is the reversible reaction between an alkanoic acid and an alkanol in the presence of a mineral acid to produce an alkanoate(formerly an ester)and water.
CH3COOH + C2H5OH-->CH3COOC2H5 +H2O(Ethylethanoate)

(1b)i-They have high resistance to chemical attack

ii-They have thermal and electrical insulation properties

iii-They have low densities
iv-They are easy to fabricate inta a wide variety of both simple and complex shapes

(1c)Components of duralumin are;
i-Aluminium(93.5%),ii-Copper(4.4%),iii-Magnesium(1.5%),iv-Manganese(0.6%)

(1f)
-Eye shades
-Laboratory coats
-Hand gloves
-Spatula
(1g)
-Ammonia is used as a refrigerant in refrigerators
-Ammonia is used in production of amine and amide
(1h)
-Cracking
-Sodium Ethanoate-
(1i)
H2S04=0
(1*2)+S+(-2)4=0
2+S-8=0
S-6=0
S=6
(1j)
-Sodium trioxochlorate(v)
-Copper(ii)tetraoxosulphate pentahydrate


(5a)
(i)-hydrogen chloride
(ii)-They are soluble in water
(iii)-They are less dense than air

(5b)
(i)
-Solubility is the amount of solute of moles in which can dissolve in 1dm^3 of solvent at standard temperature and pressure

-Saturated solution is the solution in which contains more solute than it can dissolve at a particular temperature

(ii)
-Temperature
-Surface area of solid

(iii)
Given; mass of Z=10.2g
Volume(V)=15.4cm^3
Temperature=40degreesC
Molar mass of Z=331
Mole=10.2g/331gmol
Solubility=Mole/Volume
=0.031/(15.4*1000)
=2*10^-6mol/dm^3


(5c)
(i)
- P is Ca^2a+,Calcium ion
Q is magnesium ion
Ca^(2a+)+H2(^+) + O2(^2-)->Ca(OH)2

(ii)
To the unknown substance in the container,add copper(II)tetraoxosulphate(IV)solution, If a blue precipitate is formed.This confirms the presence of water

(iii)
-Furring of kettle and boiler
-Stalagmite and Stalactite

(iv)
Na2SO4 + Ca(OH)2->CaSO4 + NaOH


(3a)
(i)
-Each member of a family has the same general molecular formular
-Each member of a family has the same method of preparation
-Each member differs in its molecular formular by CH2
(ii)
Alkanes, Alkynes

(3b)
(i)Hydroxyl group
(ii)C2H5OH
(iii)C2H5OH + CH3COOH->CH3CooC2H5 +H2O
(iv) Ethyl ethanoate

(3c)(---) means tripple bond do not write
(i)
C2H2 + Br2-> H-C (---) -> C-H+Br-Br -> H-C(Br) =C(Br)-H

(ii)
1,1,2,2, - tetrabromoethane

(iii)
-High temperature
-Presence of catalyst


(3di)
Preparation of ethanol from starch starts with fermentation .The starch granules is extracted from starch food stuff by hydrolysis and addition of enzymes. It is broken to disacharide by adding amylase
(C5H6O6)->(nH20)->C12H24O12
The maltose is formed is further broken down to fructose and glucose
Maltose=fructose + glucose By using maltase
The monnossacharide is then broken down to ethanol and carbon(iv) oxide by adding zymase
C6H12O6->(zymase)->C2H5OH+CO2


(3dii)
-It contains grant molecules
-it is polysaccaride
iii)
Starch does not reduce felhing solution because it is not a reducing agent
iv)
To the unknown substance containing the starch, add iodine solution if it turns blue black, then this confirm the presence of starch



CHEM Obj.
1-10 ADCDCCDDDB
11-20 DCABCDBCAA
21-30 BACCBCBDCD
31-40 DBDDBBCCBC
41-50 DCCDCCADAA

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