Sample Test 3

Analysis of Solid G

Test Procedure

You are provided with Solid G. Carry out the tests below and write down your observations and inferences in the spaces proovided below

  1. Place solid G in a boiling tube and dissolve in 12cm3 of distilled water. Divide the resulting solution into 4 portions for the tests below.
    • (a) Test the 1st portion with red and blue litmus papers
    • (b) To the 2nd portion, add 2M sodium hydroxide dropwise till in excess
    • (c) To the 3rd portion, add 2M ammonia hydroxide dropwise till in excess
    • (d) To the 4th portion add 2-3 drops of aqueous barium chloride

    2. 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) 1st portion + Red and Blue litmus papers
(1 mark)
(1 mark)
(b) 2nd portion + 2M NaOH dropwise till in excess
(1 mark)
(1 mark)
(c) 3rd portion + 2M NH₄OH dropwise till in excess
(1 mark)
(1 mark)
(d) 4th portion + 2 to 3 drops of aqueous BaCl2 solution
(1 mark)
(1 mark)

OFFICIAL MARKING SCHEME & EXPECTED RESPONSES

Procedure Observations Inferences
(a) 1st portion + Red and Blue litmus papers Blue litmus papers turns red and Red litmus papers remains red

(1 mark) 		Solution is acidic

(1mark)
(b) 2nd portion + 2M NaOH dropwise till in excess White precipitate soluble in excess 2M NaOH

(1 Mark) 		Al3+, Zn2+ present

(1 mark)
(c) 3rd portion + 2M NH₄OH dropwise till in excess White precipitate insoluble in excess 2M NH₄OH

(1 mark) 		Al3+ present

(1 mark)
4th portion + 2 to 3 drops of aqueous BaCl2 solution White precipitate.

(1 mark) 		SO4 2- present

(1 mark)

Identity of solid G- Aluminium Sulphate