Test Procedure

You are provided with solid R, & solution T. Carry out the tests below and write down your observations and inferences in the spaces provided.

(a)Place all solid R in a boiling tube and add about 12cm3 of distilled water to dissolve.
Divide the resulting solution into 4 portions.
- (i)To the 1st portion, add 4 drops of Sulphuric (VI) acid
- (ii)To the 2nd portion, add NaOH solution dropwise until in excess
- (iii)To the 3rd portion, add 2 drops of aqueous potassium iodide solution
- (iv)To the 4th portion, add 4 drops of solution T

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

Yellow

Workbench

VIRTUAL WORKBENCH MONITOR Selected: None

System Initialised. Select boiling tube to start step 1.

Main

T₁

T₂

T₃

T₄

STUDENT LABORATORY WORKBOOK

Procedure	Observations	Inferences
(i) 1st portion + 4 drops of 2M H2SO4	(1 mark)	(1 mark)
(ii) 2nd portion + 2M NaOH dropwise till in excess	(1 mark)	(1 mark)
(iii) 3rd portion + 2 drops of aqueous KI solution	(1 mark)	(1 mark)
(iv) 4th portion + 4 drops of the solution T.	(1 mark)	(1 mark)

OFFICIAL MARKING SCHEME & EXPECTED RESPONSES

Procedure	Observations	Inferences
(i) 1st portion + 4 drops of 2M H2SO44	White precipitate (1 mark)	Pb2+, Ca2+, Ba2+ present Awarded (0) for any contradictory ion / All the 3 ions not mentioned (1mark)
(ii) 2nd portion + 2M NaOH dropwise till in excess	White precipitate which dissolves in excess (1 Mark)	Pb2+ present (1 mark)
(iii) 3rd portion + 2 drops of aqueous KI solution	Yellow precipitate (1 mark)	Pb2+ confirmed present (1 mark)
4th portion + 4 drops of the solution T.	White precipitate (1 mark)	F contains SO42-,SO32-,Cl-,CO32- Awarded (0) for any contradictory ion / All the 3 ions not mentioned (1 mark)
		Identity of Cation in solid R- Pb2+ Identity of Solution T: Na2CO3

Sample Test 5

Analysis of Solid R