Neco Chemistry practical answers 2022

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CHEMISTRY- PRACTICAL-ANSWERS

(1)

Tabulate

Titration; | rough | 1 | 2 | 3 |

 

Final; | 20.50 | 14.00 |14.00 | 14.00 |

 

Initial; | 0.00 | 0.00 | 0.00 | 0.00 |

 

Volume of A used; | 20.50 | 14.00 |14.00 | 14.00 |

 

Volume of pipette used

=25.00cm³

 

(1a)

Average volume of A used = 14.00+14.00+14.00/3

=14.00cm³ (Va)

 

2HNO³ + X²CO³ —> 2XNO³ + H²O + CO²

 

(1bi)

Conc – of B in molldm³ = ?

Given;

Ca= 0.15molldm³

Vb= 25.00cm³

Va= 14.00cm³

Cb= ??

Na= 2

Nb= 1

 

Using;

CaVa/CbVb=Na/Nb

Cb= CaVaNb/VbNa

Cb= 0.15*14.00*1/25.00*2

Cb= 2.1/50

Cb= 0.042molldm³.

 

(1bii)

Molar mass of B =?

Using;

Conc(molldm³)= Conc(gldm³)/molar mass

0.042/1 * 4.20/m.m

m.m=4.20/0.042

m.m=100glmol

 

(1biii)

Value of x in x²(i)³=?

(2x)+12 + (16*3)= 100

2x+12+48=100

2x+60=100

2x=100-60=40

2x/2=40/2

x=20g/mol

 

(1ci)

(i)I ensure that the readings are taken at the lower meniscus

(ii)I ensure that my saliva did not enter the pipette while taking the base

 

(1cii)

Pink

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(2)

Tabulate

 

(2ai)

Under Observation;

An effervescence occurs in which a colorless and odourless gas which burns blue litmus red is evolved.

 

Under Inference;

CO² gas from CO3^²is suspected

 

(2aii)

Under Observation;

The gas turns lime water milky.

 

Under Inference;

CO² gas is confirmed.

 

(2b)

Under Observation;

Y dissolves completely in water

 

Under Inference;

Soluble salt

 

(2bi)

Under Observation;

White gelatinous PPT is formed.

 

Under Inference;

Al³+, Zn²+, Pb²+, present

 

(2bii)

Under Observation;

The white gelatinous PPT dissolve in excess NaOH

 

Under Inference;

Al³+, Zn²+, Pb²+, present

 

(2biii)

Under Observation;

White gelatinous PPT formed.

 

Under Inference;

Al³+, Zn²+, Pb²+, present

 

(2biv)

Under Observation;

The white gelatinous PPT remain insoluble in excess NH³

 

Under Inference;

Al³+, Pb²+, present.

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(3ai)

It increases the boiling point of water

 

(3aii)

It requires heat to occur.

 

(3bi)

This is because it is deliquescent.

 

(3bii)

I. Calcium oxide

II. Anhydrous copper(ii) tetraoxosulphate(vi)

 

(3ci)

Hydrogen Chloride

 

(3cii)

I. To separate a mixture of immiscible liquids

II. To collect gases.

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Completed!.