Sample Test 15

Analysis of Solid Y

Test Procedure

You are provided with solid Y. Divide the solid into 2 portions

  • (a)Transfer the first portion into a clean dry boiling tube. Heat the solid gently and test the gases produced using moist litmus papers.
  • (b)Transfer the 2nd portion of solid Y into cleaned boiling tube. Add 10cm3 of distilled water. Shake the mixture. Divide the solution into 4 test tubes
    1. i.To the 1st portion, add 2M sodium hydroxide dropwise until in excess
    2. ii. To the 2nd portion, add aqueous ammonia solution dropwise until in excess
    3. iii.To the third portion, add sodium hydrogen carbonate
    4. iV.To the 4th portion, add few drops of barium chloride solution followed by 3 drops of dilute hydrochloric acid

Tips: To start, ...click on boiling tube in the display rack to select it before placing the sample.
Follow the procedure sequentially and the sytem monitor instructions.

Tips on the system color code

Colourless Solution

White Precipitate

Workbench

VIRTUAL WORKBENCH MONITOR Selected: None
System Initialised. Select boiling tube to start step 1.
B.T
T1
T₂
T₃
T₄

STUDENT LABORATORY WORKBOOK

Procedure Observations Inferences
(a) Describe the appearance of solid P.
(b) About one third of the substance P in a dry test-tube and heated strongly
(c) To the remaining substance P + about 10cm3 of distiled water
(d)
i. Added 2 to 3 drops of aqueous barium nitrate solution to the mixture
ii. Added 5 drops of dilute nitric (v) acid to the mixture
iii. Added to the mixture, aqueous sodium hydroxide dropwise until in excess
iii. Give the formula of the cation and anion present in substance P

OFFICIAL MARKING SCHEME & EXPECTED RESPONSES

Procedure Observations Inferences
(a) Describe the appearance of solid P. Colourless vapour given off which condenses to form colourless droplets

White resiidue

(1 mark) 		Hydrated salt/Compound contains water of crystallization.

(1mark)
(b) About one third of the substance P in a dry test-tube and heated strongly Colourless vapour given off which condenses to form colourless droplets

White residue

(1 Mark) 		Hydrated salt/water of crystallization

(1 mark)
(c) To the remaining substance P added about 10cm3 of distiled water Solid dissolves to form a colouress solution

(1 mark) 		Soluble salt/soluble compound

absence of coloured ions

(1 mark)
i. Added 2 to 3 drops of aqueous barium nitrate solution to the mixture White precipitate.

(1 mark) 		S042-, SO32-,CO32- present

(1 mark)
ii. Added 5 drops of dilute nitric (v) acid to the mixture No effervescence

(1 mark) 		SO42- present.

SO32-,CO32- absent.

(1 mark)
iii. Added to the mixture, aqueous sodium hydroxide dropwise until in excess White precipitate insoluble in excess

(1 mark) 		Mg2+ present.

(1 Mark)
(e) Give the formula of the cation and anion present in substance P Cation: Mg2+

(1 mark) 		Anion: SO42-

(1 Mark)

Identity of solid G- Hydrated Ammonium Aluminium Sulphate