Test Procedure

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

(a) Place all solid L in a dry boiling tube and heat it strongly. Test the gases produced with wooden splint. Keep the residue for the tests in (b).
(b) Allow residue from (a) above to cool for about three minutes. Add 5-6 drops of dilute nitric (V) acid, then add distilled water until the test tube is three quarters full. Filter the mixture into a boiling tube then add more distilled water to the filtrate until the boiling tube is half full. Shake well. Use the solution obtained for the tests below:
- (i) To 2cm3 of solution in a test tube add 2M sodium hydroxide solution dropwise till in excess
- (ii) To another 2cm3 of solution in a test tube add aqueous ammonia dropwise till in excess
- (iii) To another 2cm3 of solution in a test tube, add 2M Sulphuric (vi) 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.

Main

T₁

T₂

T₃

STUDENT LABORATORY WORKBOOK

Procedure	Observations	Inferences
(a) Solid L in a boiling tube + heated strongly + tested the gases produced with a glowing wooden splint.
(b) Allowed the residue to cool + added 5-6 drops of HNO3 + filtered + added distilled water to the filtrate to half full
(b) (i) To 2cm3 of the solution + 2M NaOH solution dropwise till in excess
(ii) To another 2cm3 of the solution + aqueous ammonia dropwise till in excess
(iii) To another 2cm3 of the solution + 2M sulphuric acid

OFFICIAL MARKING SCHEME & EXPECTED RESPONSES

Procedure	Observations	Inferences
(a) Solid L in a boiling tube + heated strongly + tested the gases produced with a glowing wooden splint.	Colourless gas that relights a glowing splint (1 mark)	ClO3-, NO3-,MnO4-, O2- present (1 mark)
(b) Allowed the residue to cool + added 5-6 drops of HNO3 + filtered + added distilled water to the filtrate to half full	Colourless filtrate/Colourless solution after filtration (1 Mark)
(b) (i) To 2cm3 of the solution + 2M NaOH solution dropwise till in excess	White precipitate soluble in excess (1 mark)	Al3+,Pb2+, Zn2+ present (1 mark)
(ii) To another 2cm3 of the solution + aqueous ammonia dropwise till in excess	White precipitate insoluble in excess (1 mark)	Pb2+ Al3+, present (1 mark)
(iii) To another 2cm3 of the solution + 2M sulphuric acid	White precipitate (1 mark)	Pb2+ present
		*Identity of solid L- Lead (iv) oxide*

Sample Test 14