Test Procedure

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

(a) Place half of H in a boiling tube and add distilled water until the boiling tube is half full. Shake until solid H dissolves. Use it as solution H in the experiments below.
- (i) Put the remaining solid H in the boiling tube and add few drops of 2M NaOH provided. Heat gently and test the gas produced with red and blue litmus papers
- (ii) To about 2cm3 of H, add 2M sodium hydroxide dropwise until in excess.
- (iii) To about 2cm3 of solution H in a test tube, add ammonium solution dropwise until in excess
- (iv) To about 2cm3 of solution H, add few drops of dilute Sulphuric acid
- (v) To about 2cn3 of solution H add 4-5 drops of barium nitrate solution provided

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) (i) Solid H in boiling tube + few drops of 2M NaOH + Heated gently & Tested with red & blue litmus papers
(ii) To about 2cm3 of solution H + 2M NaOH dropwise until in excess
(iii)To about 2cm3 of solution H + ammonium solution dropwise until in excess
(iv) To about 2cm3 of solution H + few drops of dilute sulphuric acid
(v) To about 2cm3 of solution H + 4-5 drops of barium nitrate solution

OFFICIAL MARKING SCHEME & EXPECTED RESPONSES

Procedure	Observations	Inferences
(a) (i) Solid H in boiling tube + few drops of 2M NaOH + Heated gently & Tested with red & blue litmus papers	Red litmus paper turns blue. Blue litmus papers remains blue. Colouress vapour condenses on the cooler parts of the boiling tube. (1 mark)	NH4+ present(Tied to change in red litmus paper to blue) Hydrated salt/Compound contains water of crystallization(Tied to colourless liquid formed on coller parts of the boiling tube) (1mark)
(ii) To about 2cm3 of solution H + 2M NaOH dropwise until in excess	White precipitate soluble in excess (1 Mark)	Al3+,Zn2+, Pb2+ present (1 mark)
(iii)To about 2cm3 of solution H + ammonium solution dropwise until in excess	White precipitate insoluble in excess (1 mark)	Al3+, Pb2+ present (1 mark)
(iv) To about 2cm3 of solution H + few drops of dilute sulphuric acid	No white precipitate (1 mark)	Al3+ present (1 mark)
(v)To about 2cm3 of solution H add 4-5 drops of barium nitrate solution provided	White precipitate insoluble in excess ammonium hydroxide (1 mark)	SO42- present (1 mark)
		*Identity of solid H- Hydrated Ammonium Aluminium Sulphate*

Sample Test 19