EXAMKING CONTACTS
  08065582389 || +2348065582389

NECO GCE 2021 CHEMISTRY (ALTERNATIVE TO PRACTICAL) ANSWERS

Like Comment

COMPLETED
 
1ai)
-inconsidtent reading of the burette to the nearest whole number
-consistently reading burette to one decimal number
-arithmetic error
-lack of unit
-non concordant values
 
1aii)
Average Titre=24.55+22.60+22.50/3
=69.65cm³/3
=23.216cm³
 
1aiii)
Na²Co3+2HCL===>2Nacl+H20+Co2
 
1aiv)
Methyl Orange.
 
1av)
It’s a titration Between strong acid and Strong Base
 
1avi)
Pink
1bi)
CA=0.0050moldm-³,Na=2
CB=? VB=25cm³, Nb=1
VA=23.21cm³
 
CAVA= NA
===== ===
CBVB NB
 
0.050X23.21=2
CBX25.00 1
 
CBX2X25.00=0.0050X23.21X1
 
CB=1.1605/50 moldm³
CB=0.023moldm³
 
1bii)
Molar mass of Na2 Co3
2[Na]+ C+3 [O]
=2(23)+12+3+(16)
=46+12+48 gmol-1
Molar Mass of Na2Co3=106gmol-1
 
Concentration Of Na2Co3 in gdm-3
=CBx Molar Mass
=0.023×106 gdm-3
=2.438gdm-1
 
1biii)
1 Mole Of Co2=22.4cmd-3
Mole Ratio Of B(Na2Co3):Co2= 1:1
 
0.023mole=0.023mole
1mole of Co2=22.4dm³
 
0.023mole =22.4×0.023
=0.52dm³
 
 
1biv)
n=CV
n=0.05×23.21
n=1.16mole
 
=======================================
NO2a)
Observation| Inference
i) | Fe³+Present
ii) | Fe³+ Present
iii)brown
Solution ——-
Observed
 
iv)Red blood Cell ———- Observed.
 
2b)
i) |Co3²-,So3²- S²- may Present
 
ii) | Co3²-,So3² S²- may present
 
Iii)
KmnO4 Decolour Rised
 
 
 
2c)
i)Effervescence of greenish-yellow gas turns blue litmus red
ii)The Precipitate dissolved…
 
 
========================================
 
(3ai)
(i)To prevent sunlight Ray’s from affecting the solutions
 
(ii)To prevent the sucking back of water into the hot flask.
 
(iii) Because it is a component of glass
 
(iv)NaOH + CO² —> NaHCO³
 
(3bi)
(i)Heat iodine crystal
(ii)NH⁴Cl
 
(3bii)
(i)Stationary phase
(ii)Morning phase
 
*3aiv) 2NaOH + SiO3 —–> NaSiO3 + H2O*
 
 
 
 
 
COMPLETED
 

You might like

About the Author: ExamKing Ceo

Leave a Reply

Your email address will not be published.

JOIN OUR TELEGRAM CHANNEL FOR FREE ANSWERS

X