CHEMISTRY – PRACTICAL

2 )

Test

I . Solution + NaOH in excess

Ii . Solution + NH 3 in excess

Iii . Solution + BaCl + HCl in excess

Iv. Solution + AgNO 3

Observation

I . White gelatinous precipitate soluble in excess NaOH

Ii . White gelatinous precipitate soluble in excess NH 3

Iii . White precipitate formed with BaCl2 which dissolves in excess HCl

iv . White precipitate formed with AgNO 3

Inference

I . Zn , Pb, or Al is present

Ii . Zn confirmed

Iii . CO3 , Cl , SO4 present

Iv. Cl present

( 1 ai)

Burrette readings/ cm 3 : | titre 1 | titre 2 | titre 3

Final readings | 33 . 20 | 49. 60 | 1 . 50

Initial readings | 16 . 40 | 16. 40 | 16. 65

( 1 aii )

Average volume of acid used

= 16 . 40 + 16 . 40+ 16. 65 ( cm 3 ) / 3

=49 . 45cm 3 / 3

=16 . 48cm 3

( 1 b )

( I ) Concentration of Y ( OH ) 2 . XH 2 O in mol/ dm 3

Using CAVA / CBVB = a/ b

CA = 0 . 025 mol / 0 . 25 dm 3 = 0 . 1 mol

VA = 16. 48 cm 3

CB = ?

VB = 25. 00 cm 3

a = 1 mol

b = 2 moles

. : . CAVA / CBVB =a/ b

CB = CAVA * B / VB *a

= 0 . 1 mol/ dm 3 * 16 . 48 cm 3 * 2 moles / 25 . 00 * 1 mol

CB = 3 . 296 / 25

CB = 0 . 131 mol / dm3

3 a)

I ) Desiccator – usefor preserving moisture sensitive items

ii ) Volumetric flasks are used for precise dilutions and preparation of standard solutions .

iii ) Glass rod are used to mix chemicals and liquids for laboratory purposes .

3 ii )

i ) Amphoteric is Al2 O 3

ii ) Neutral oxide is H 2 O

3 iii )

Crystallization

3 b )

1 ) hno 3 aq to cuco 3 solid . a light blue solid ,

precipitates is formed

2 ) acidified kmno 4 to c2 h 4 . c2 h 4 is oxidized to ethane- 1 , 2 – diol

3 ) iodine solution to a paste of unripe plantain . a bluish – black color is produced with iodine