HOMEJAMB WAEC
POST UTMENECO SCHOLARSHIP

Easy & Fast Contact??
08095156374 Call 08095156374

Send us an Email

Examtemple4life@gmail.com


CLICK EXPO CATEGORY NOW!!!


« | »

You are here in Home » NECO

Confirmed Questions & answers for Neco chemistry practical


neco logo runs expo image 2018 time table
NECO-CHEMISTRY-PRACTICALS-ANSWER
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
================================
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
================================
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
===============================
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
(1a)
Tabulate:

Titrations |Rough|1st |2nd |3rd |
Final burette reading |18.00|15.60|17.40|20.50|
Initial burette reading |0.00 |0.00 |2.00 |5.00 |
volume of Acide used |18.00|15.60|15.40|15.50|

(1ai)
Average volume of Acid used
VA = (VA1 + VA2 + VA3)cm3/3
VA = (15.60+15.40+15.50)/3
VA = 46.50/3
VA = 15.50cm3

(1aii)
2HCl(aq)+Na2CO3(aq)–>2NaCl(aq)+H2O(l)+CO2(g)

(1bi)
CA VA/CB VB =NA/NB
0.1moldm^-3 x 15.50cm3/CB x 25cm3 x 2/1
CB x 25cm3 x 2 = 0.1moldm^-3 x 15.50cm3 x 1
CB x 50 = 1.55
CB = 1.55/50 = 0.031moldm^-3

(1bii)
25cm^3—->0.031mole
1000cm^3—->x
x=1000*0.031/25=31/25
x=1.24moldm^-3

(1biii)
concentration in mold^-3 =Con glm^3 /molar mass
0.031moldm^-3=x/106
x=0.031*106
x=3.286gldm^3
(2a)
Tabulate

(2ai)
OBSERVATION: C dissolves in water
INFERENCE: C is a soluble salt

(2aii)
OBSERVATION: White precipitate formed
INFERENCE: CO3²-, SO3²-, SO4²- suspected

(2aiii)
OBSERVATION: White ppt dissolves in excess of dil HCl
INFERENCE: CO3²- , SO3²- suspected

(2bi)
OBERSVATION: Effervescence occurs with the evolution of a gas
INFERENCE: CO3²- present

(2bii)
OBERSVATION: Solutions turns to pink
INFERENCE: CO3²- Confirmed
Refresh this page every 5 minutes to display.the answers ….

Loading

Loading

Loading

Posted by Da WebGeek


Posted by on June 5, 2018 in NECO

Tags: , , ,

Comment Section

Comment Counts: (1)

  1. Amara posted:

    Hi, very nice website, cheers!
    ——————————————————
    Need cheap and reliable hosting? Our shared plans start at $10 for an year and VPS plans for $6/Mo.
    ——————————————————
    Check here: https://www.good-webhosting.com/

    on Sep 4, 2019 at 1:01 pm

Leave a Reply

Your Name

Your Message


NOTE:- Dont Drop Your Comment Twice, After Dropping Your Comment, Keep Calm, It Will take 5mins Before it appears.

« | »





best exam website solution in nigeria

About | Disclaimer | Privacy | Contact


SOCIAL MEDIA

Facebook | Instagram | Twitter | Youtube