Sample Test 1

Analysis of Solid M

Test Procedure

You are provided with Solid M. Carry out the tests below and write down your observations and inferences

  1. Place half of solid M in a clean dry boiling tube and heat strongly. Test the gases produced using a glass rod dipped into 2M hydrochlorc acid.
  2. Place the remaining half of solid M in a clean dry boiling tube and dissolve in 12cm³ of distilled water. Divide the resulting solution into 4 portions (T₁, T₂, T₃ & T₄):
    • (a) To the 1st portion T1, add 3 drops of aqeous barium chloride solution.
    • (b) To the 2nd portion T2, add drops of dilute Nitric(V) acid, followed by 2-3 drops of lead(II) nitrate solution.
    • (c) To the 3rd portion T3, add 2M sodium hydroxide solution dropwise till in excess.
    • (d) To the 4th portion T4, add 2M aqueous ammonia solution dropwise till in excess.

Tips: Always Click to select on target Boiling/Test tube in the display rack to perform target action.
Follow the procedure sequentially and the sytem monitor instructions.

Tips on the system color codes:

Colourless

White

Workbench

VIRTUAL WORKBENCH MONITOR Selected: None
System Initialised. Select boiling tube to start step 1.







BT
T₁
T₂
T₃
T₄

STUDENT LABORATORY WORKBOOK

Procedure Observations Inferences
1. Heating Solid M & Testing Gas with Conc. HCl
(1 mark)
(1 mark)
2. (a) Portion 1 + 2-3 drops of BaCl₂
(1 mark)
(1 mark)
2. (b) Portion 2 + Dilute HNO3 followed by 2-3 drops of Pb(NO3)2
(1 mark)
(1 mark)
2. (c) Portion 3 + NaOH dropwise till in excess
(1 mark)
(1 mark)
2. (d) Portion 4 + NH₄OH dropwise till in excess
(1 mark)
(1 mark)

OFFICIAL MARKING SCHEME & EXPECTED RESPONSES

Procedure Observations Inferences
1. Heating Solid M & Testing Gas with Conc. HCl Colourless liquid forms on the cooler parts of the boiling tube/Colourless vapour condenses on the cooler parts of the boiling tube.

Gas produced which forms white fumes with hcl.

(1 mark) 		Hydrated salt/Compound contains water of crystallization(Tied to colourless liquid formed on coller parts of the boiling tube)

NH4+ present(Tied to white fumes)

(1mark)
2. (a) Portion 1 + 2-3 drops of BaCl₂ White precipitate

(1 Mark) 		SO4 2-, SO3 2-,CO3 2- present

(1 mark)
2. (b) Portion 2 + Dilute HNO3 followed by 2-3 drops of Pb(NO3)2 Whie precipitate

(1 mark) 		SO4 2- present

(1 mark)
2. (c) Portion 3 + NaOH dropwise till in excess White precipitate that dissolves in excess sodium hydroxide

(1 mark) 		Al3+, Zn2+ present
Note: Pb2+ is contradictory because solid M is seen containing S04 2- ions and yet dissolved in water to colourless solution; hence ruling out Pb2+ since PbSO4 is insoluble in water.

(1 mark)
2. (d) Portion 4 + NH₄OH dropwise till in excess White precipitate insoluble in excess ammonium hydroxide

(1 mark) 		Al3+ present

Identity of solid M- Hydrated Ammonium Aluminium Sulphate