Test Procedure

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

(a) Describe the appearance of solid R
(b) Place a portion of R in a dry test tube and heat strongly. Test any gases produced using red and blue litmus papers.
(c) Place the remainder of solid R in a boiling tube and add 10cm3 of distilled water. Shake well. Divide the solution into 4 portions and use in the tests below.
- (i)Test the 1st portion with red and blue litmus papers
- (ii)To the 2nd portion, add aqueous sodium hydroxide dropwise till in excess
- (iii)To the 3rd portion, add 2cm3 of dilute hydrochloric acid
- (iv)To the 4th portion, add few drops of aqueous lead (ii) nitrate
- (iv)To the 5th portion, add 5 drops of aqueous sodium hydroxide. Add a piece of aluminium foil provided to the mixture and shake. Warm the mixture and test any gases produced with both blue and red litmus papers

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.

SOLID R

B.T

STUDENT LABORATORY WORKBOOK

Procedure	Observations	Inferences
(a) Describe the appearance of R
(b) Solid R in dry test tube + Heating + Test gas produced with red & blue litmus papers
(c) Solid R in boiling tube + 10 cm3 distilled water
(i) Test 1st Portion with red & blue litmus papers
(ii) 2nd portion + aqueous NaOH dropwise till in excess
(iii) 3rd portion + 2cm3 dilute HCL
(iv) 4th portion + few drops of Pb(NO3)2
(v) 5th portion + aqueous NaOH + aluminium foil + warming. Test gas produced with both red & blue litmus papers

OFFICIAL MARKING SCHEME & EXPECTED RESPONSES

Procedure	Observations	Inferences
(a) Describe the appearance of R	colourless crystalline solid (1 mark)
(b) Solid R in dry test tube + Heating + Test gas produced with red & blue litmus papers	Brown fumes, colourless liquid on cooler parts, red litmus paper remains red and blue litmus paper changes to red Blue litmus paper changes to red Whie residue (1 Mark)	NO3- present Acidic gas produced. (tied to blue litmus paper changes red) (1 mark)
(c) Solid R in boiling tube + 10 cm3 distilled water	Solid R dissolves to form a colourles solution (1 mark)	Cu2+, Fe2+, Fe3+ present Cloloured ions absent (1 mark)
(i) Test 1st Portion with red & blue litmus papers	Red litmus paper remains red Blue litmus paper changes to red. (1 mark)	Solid R is acidic (1 mark)
(ii) 2nd portion + aqueous NaOH dropwise till in excess	White precipitate soluble in excess (1 mark)	Al3+, Pb2+, Zn2+ present.
(iii) 3rd portion + 2cm3 dilute HCL	No white precipitate (1 mark)	Zn2+, Al3+ present.
(iv) 4th portion + few drops of Pb(NO3)2	No white precipitate (1 mark)	SO42- present.
(v) 5th portion + 5 drops of NaOH followed by aluminium foil and warming. Test gas produced with both red litmus papers and blue litmus papers	Effervescence of a gas with a punjent smell Red litmus paper changes to blue and blue litmus paper remains blue (1 mark)	NO3- present. (1 mark)
		*Identity of solid R: Aluminium Nitrate - Al(NO3)3*

Sample Test 13