NECO-CHEMISTRY-PRACTICALS-ANSWER

NECO-CHEMISTRY-PRACTICALS-ANSWERS

Test                                               Observation                                                             inference            

1.    C+ distilled  water                  c dissolved in distilled H2O to give                             C is a soluble salt

                                                    a colourless solution        

+litmus paper                         C has no action on blue or red litmus    C is a neutral  salt

                                                   paper 

2.    C+ BaCl2                                   white precipitate is observed 

+ dilute HCL                             precipitate dissolved, effervesces 

                                                   Occur with a colorless, odorless  gas

                                                    Which turns lime water milky

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
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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
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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.
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Completed
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