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Neco 2018 Chemistry Practical Answers – May/June Expo
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Posts: 5
chidusky
chidusky (m)
0 year ago

CLICK HERE FOR THE no.1 IMAGE
(1ai)
Tabulate
Titrations|Rough|first(1)|second(2)|third(3)
Final burette reading-|20.50|14.90|15.00|15.10|
initial burette reading- |0.00|0.00|0.00|0.00|
volume of Acide used- |20.5|14.90|15.00|15.10|

(1ai)
average volume of Acid used
1st+2nd+3rd/3
14.90+15.00+15.10/3=45/3=15cm^3

(1aii)
2HCL(aq)+Na2CO3(aq)---->2NaCl(aq)+H2O(aq)+CO2(aq)

(1bi)
CA VA/CB VB =NA/NB
0.1moldm^-3*15cm^3/CB*25cm^3 *2/1
CB * 25cm^3*2=0.1moldm^-3*15cm^3*1
CB * 50=1.5
CB=1.5/50=0.03moldm^-3

(1bii)
25cm^3---->0.03mole
1000cm^3---->x
x=1000*0.03/25=30/25
x=1.2moldm^-3

(1biii)
concentration in mold^-3 =Con glm^3 /molar mass
0.03moldm^-3=x/106
x=0.03*106
x=3.18gldm^3
====!=======================
CLICK HERE FOR THE no.2 IMAGE
(2a)
Tabulate

(2ai)
-OBSERVATION-
i)C dissolves in water
ii)formation of white precipitate
iii)White precipitate dissolves in itel

-INFERENCE-
i)C is soluble in water
ii)CO3^-2,SO4^-2,SO3^2- suspected
iii)CO3^2-,SO3^2-, suspected

(2bi)
-OBERSVATION-
i)effervescence occurs with the evolution of a gas
ii)the solutions turns to pink

-INFERENCE-
i)CO3^2-,SO3^2-, suspected
ii)CO3^2-,Confrimed
==================================

CLICK HERE FOR THE no.3 IMAGE
(3ai)
Zinc chloride reaction with HaOH form white gelatinous precipitate solution in excess HaOH.
Ammonium trioxocarbonate(iv) on reaction with HaoH evolves a gas which turns red litmus paper blue and lime water milky.
Calcium trioxocarbonate(iv) on reaction with HaoH forms white powdery precipitate insoluble in excess HaOH.

(3aii)
i)liquid substance--> crystallization
ii)Solid substance--> precipitation

(3bi)
i)Evaporation takes place at all temperatures, while boiling occurs at a particular temperatur (at boiling point).
ii)Evaporation takes place from the surface, whereas the entire liquid boils.

(3bii)
Carbon(iv)oxide does not support combustion

(3ci)
molar solution is an aqueous solution that contains 1 mole (gram-molecular weight) of solute in 1 liter of the solution.

(3cii)
Indicator

(3ciii)
i)methyl orange
ii)Phenolphthalein.
=====================
COMPLETED

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Mikkytek
Mikkytek (m)
0 year ago
Chidusky pls try helping even if its just 2 of 3 questions in chemistry practical 2day like u often care in waec 4 those who re writing exams
Stonecod
Stonecod (m)
0 year ago
Gud morin
DrNice
DrNice (m)
0 year ago
Thanks
timothyjimoh
timothyjimoh (m)
0 year ago
i have subscribe for english ooo no confirmation yet from jimoh timothy
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