NECO 2017 Chemistry Practical Solution Answer – June/July Expo

NECO Chemistry Practical Questions and Answer – June/July 2017 Expo Runz

2017 NECO CHEMISTRY PRACTICAL SOLUTION

NO1)
Note:

Candidates are strongly advised to check which size of pipette was used by their school.

We used 25cm³

——————————-

If your school used 20cm³, all you need do is use it in place of 25cm³ anywhere we used it and calculate accordingly
NOTE:ALL MAKE USE OF YOUR SCHOOL ENDS POINT

Volume of Pipette used 25.0cm^3

Titration | Rough | First | Second | Third
Final burette reading (cm^3) | 22.50 | 45.10 | 32.65 | 27.60
Intial burette reading (cm^3) | 0.00 | 22.50 | 10.00 | 5.00
Volume of A used (cm^3) | 22.50 | 22.60 | 22.65 | 22.70

1a) Average volume of A = 22.60 + 22.65 + 22.70/3

= 22.65cm^3

1bi) GIVEN: CB = 0.10moldm^-3
VB = 25cm^3
CA = ?
VA = 22.65cm^3

Equation of reaction:
H2C2O4(aq) + 2NaOH(aq) ====> Na2C2O4(aq) + 2H2O(l)
hence, nA = 1
Nb = 2

Using CAVA /CBVB = nA/nB
CA = CBVBnA/VanB
=0.10 × 25 × 1/22.65 × 2

CA = 0.055 moldm^-3

Concentration of A in moldm^-3 = 0.055

bii) Using:
gram concentration = molar concentration × molar mass
conc. Of A in gdm^-3 = 0.055 × [(1 × 2) + (12 × 2) + (16 × 4)]
= 0.055 × 90
= 4.95gdm^-3
======================

No2 solution

2a)
TEST
X + 5cm of distilled water, Divide the solution into 4 portion

OBSERVATION
Salt X is soluble in distilled water

INFERENCE
Salt X is soluble salt
=======================
2bi)
Test
-To the first portion, Add dilute NaOH in drop
-then in excess

OBSERVATION
-White precipitate solution is formed
-The white precipitate is soluble

INFERENCE
Zn^2+ Pb^2+ and AL^3+ are present
=====================
2bii)
TEST

-To the 2nd portion add dilute NH3 solution in drop
-then in excess

OBSERVATION

White gelatinous precipitate is formed which is insoluble in excesa

INFERENCE

Zn^2+,Pb^2+ and Al^3+ are present
======================
2biii)
TEST
To the 3rd portion, Add dilute HCL in drops
-then in excess
-heat the solution

OBSERVATION
White precipitate is formed which Dissolved on heating and re-appears on cooling

INFERENCE

Pb^2+ confirmed
======================
2ci)
TEST
Sample Y + concentrated HNO3

(Cii)
Heat the product formed in (ci)

OBSERVATION
Dirty white curd is formed
===========
It turn to yellow colouration on heating
INFERENCE
Protein is present

====================
2ciii)
TEST

Add concentrated NH3 to the product in (cii)

OBSERVATION
The product in (Cii) turns to orange colour

INFERENCE

Protein is present
=======================

No3

3ai)
i) SO2 change the colour of acidified K2Cr2O7 solution from Orange to green when it is passed through it by changing to Cr2(SO4)3
solution

ii) when zinc dust is added to CuSO4 solution, the solution turn from Blue to white

3aii)
i)Due to the formation of Cr2(SO4)3 solution

ii)Due to the formation of white ZnSO4 since zinc is higher in electrochemical series

3b)
DRAW and label a diagram for a set up that can be used to separate suspension of chalk dust in water

CLICK HERE FOR 3B ANSWER

=========================

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============================

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21 Comments on NECO 2017 Chemistry Practical Solution Answer – June/July Expo

  1. Fumi micheal // June 11, 2017 at 10:40 pm // Reply

    I NEED IT

  2. I need it please

  3. I need it

  4. lawal opeyemi // June 12, 2017 at 8:17 am // Reply

    I need it

  5. send Chemistry pls

  6. Txs but please my brzs we send us after 20 hours bcs you know naija is no money that is why some of us we not subcribtion please

  7. i appreciate …wish you all the best..
    Thanks

  8. yousup habeeb // June 12, 2017 at 11:03 am // Reply

    Thanks alot

  9. Thank you

  10. your titre value is wrong.
    correct titre value is 16.4cm^3

  11. Tanks 4ur help

  12. I need biology practical

  13. Tanz a lot but biology practical pls

  14. Isaac Christian // June 12, 2017 at 4:06 pm // Reply

    Pls help me

  15. Thanks a lot
    Please we need biology practical

  16. adhezoghene // June 12, 2017 at 6:10 pm // Reply

    tanx alot i need biology practical too

  17. good

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