Test Procedure

You are provided with Solid H. Carry out the tests below and write down your observations and inferences

1. Place half of solid H in a dry boiling tube and heat strongly. Test the gases produced with litmus papers
2. Place the remaining half of solid H in a boiling tube and add 10cm³ of distilled water. Divide the resulting solution into 3 portions (T₁, T₂, T₃, T₄):
- (a) To the first portion, add sodium hydroxide until in excess
- (b) To the second portion, add 2 to 3 drops of barium nitrate
- (c) To the third portion, add 2 to 3 drops of hydrogen peroxide followed by aqueous ammonia dropwise until in excess.

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 H in boiling tube, heated strongly & Testing Gas with litmus papers
(b) Solid H in boiling tube + 10cm3 distilled water
(i) 1st Portion + NaOH dropwise till in excess
(ii) 2nd Portion + 2-3 drops of Barium nitrate
(iii) 3rd portion + 2-3 drops of hydrogen peroxide followed by aqueous NH4OH dropwise till in excess

OFFICIAL MARKING SCHEME & EXPECTED RESPONSES

Procedure	Observations	Inferences
(a) Heating Solid H & Testing Gas with Litmus Papers	Colourless liquid forms on the cooler parts of the boiling tube/Colourless vapour condenses on the cooler parts of the boiling tube. Gas produced which turns red litmus paper blue and blue litmus paper remains blue. (1 mark)	Hydrated salt/Compound contains water of crystallization(Tied to colourless liquid formed on coller parts of the boiling tube) NH4+ present(Tied to changes on red litmus paper) (1mark)
(b) Solid H in boiling tube + 10cm3 distilled water	Colored solution formed (1 Mark)	Fe2+, Cu2+, Fe3+ present (1 mark)
(i) 1st Portion + NaOH dropwise till in excess	Green precipitate insoluble in excess (1 mark)	Fe2+ present (1 mark)
(ii) 2nd Portion + 2-3 drops of Barium nitrate	White precipitate formed (1 mark)	SO4 2-, CO3 2-, SO3 2- present (1 mark)
(iii) 3rd portion + 2-3 drops of hydrogen peroxide followed by aqueous NH4OH dropwise till in excess	Yellow/brown solution fomed Brown precipitate insoluble in excess NH4OH (1 mark)	Fe2+ oxidised to Fe3+ by H2O2 Fe3+ formed. (1 mark)
		*Identity of solid G- Hydrated Ammonium Ferrous Sulphate*

Sample Test 9