Free Nabteb Gce 2016 Chemistry Practical Answers – Nov/Dec Expo

Free Nabteb Gce 2016 Chemistry Practical Answers – Nov/Dec Expo

1ai)
M. Mass of A = H2C2O4 2H2O
= 1*2+12*2+16*4+2(1+2*16)
=2+24+64+36
Mass of A= 126g
Therefore
Cone A in mol/dm³ = 12.55/126 = 0.996 mol/dm³
1aii)
Ca= 0996mol/dm³
Va=24.20cm³
Cb= ?
Vb= 25.00cm³
na= 1
nb= 2
CaVa/CbVb = na/nb
Cb = CaVana/Vbna
= 0.996*24.20*2/25*1
Cb= 0.1928mol/dm³
1aiii)
M. Mass of B = Conc B g/dm³/Conc B mol/dm³
= 7.72/0.1928
Molar mass of B = 40g
1aiv)
Molar mass of B = XOH =40
X+16+1=40
X= 40-17
= 23
Therefore X is a sodium indicator=>
1av)
Pale pink
1b)
The end point will be affected, since the solution is been diluted more by distiled water.
1c)
A secondary standard solution is a solution that has its concentration measured by titration with a primary standard solution with known concentration.
1d)
Diagram.
From gidifans
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2a)
Inference: X is a mixture of soluble and insoluble salt
2bi)
Inference: CO^2- ,
3
SO^2 ,
4
CL^-
2bii)
Observation:
Colurless gas involved with choking smell, turns litmus red to blue from gidifans
2c)
Observation: it turns damp blue litmus paperred and finally breaches it
2di)
Solving…..
2dii)
C2H5COOH
2diii)
C3H2OH, C2H5COOH
2iv)
C2H5CH3
From gidifans
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3ai)
The phosphorus has used up the oxygen present so the volume of water rises
3aii)
40cm³
3aiii)
CO2
O2
N2
3b)
The solution turns blue because chlorine
Displaces iondine from the iondide
3ci)
Filtration
From gidifans
3cii)
Chromatography
3ciii)
Melting point or boiling point
3d)
Y(powered charcoal)
X (charcoal chips)
Z (lump charcoal)
I.e Y burns faster than X and X burns faster than Z
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