Sample Test 6

Analysis of Solid E

Test Procedure

You are provided with solid E. Carry out the tests below and write your observations and inferences in the spaces provided.

  • (i) Place about half of solid E in a clean dry boiling tube. Heat strongly and test the gases produced with both blue and red litmus papers.
  • (ii) Place the other half of solid E in boiling tube and dissolve in about 10cm3 of distilled water. Divide the resulting solution into 3 portions T1, T2 & T3.
    • (i) To the 1st portion, add aqueous ammonium hydroxide dropwise until in excess
    • (ii) To the 2nd portion, add Sodium chloride solution provided
    • (iii) To the 3rd portion, add 2 to 3 drops of barium nitrate
    • (iv) To the mixture obtained in the 3rd portion, add 2cm3 of dilute nitric (v) 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

    White

Workbench

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







BT
T₁
T₂
T₃

STUDENT LABORATORY WORKBOOK

Procedure Observations Inferences
(i) About half of Solid E in a clean dry test tube + Heated Strongly + Tested gases produced with both blue & red litmus papers
(ii) Remaining Solid E in boiling tube + 10 cm3 distilled water. Divided into 4 portions
(i) 1st portion + aqueous NH4OH dropwise until in excess
(ii) 2nd portion + NaCl solution provided
(iii) 3rd portion + 2 to 3 drops of Ba(NO3)2 solution
(iv) Mixture obtained in the 3rd portion + 2cm3 of dilute nitric (v) acid

OFFICIAL MARKING SCHEME & EXPECTED RESPONSES

Procedure Observations Inferences
(i) About half of Solid E in a clean dry test tube + Heated Strongly + Tested gases produced with both blue & red litmus papers colourless gas with a pungent smell that turns red litmus paper blue & no effect on blue litmus paper

Colourless liqud forms on the cooler parts of the test tube

(1 Mark) 		NH4+ present (tied to red litmus paper turning blue)

Hydrated compound / contains water of crystallisation

(1 mark)
(ii) Remaining Solid E in boiling tube + 10 cm3 distilled water. Divided into 4 portions
(i) 1st portion + aqueous NH4OH dropwise until in excess 		White precipitate insoluble in excess

(1 mark) 		Al3+, Pb2+ present

(1 mark)
(ii) 2nd portion + NaCl solution provided No white preciptate

(1 mark) 		Al3+ present

(1 mark)
(iii) 3rd portion + 2 to 3 drops of Ba(NO3)2 solution White precipitate.

(1 mark) 		SO42-, SO32-, CO32- present
(iV) Mixture obtained in the 3rd portion + 2cm3 of dilute nitric (v) acid White precipitate persists

(1 mark) 		SO42- confirmed present

Identity of solid N: Hydrated Ammonium Aluminium Sulphate