Test Procedure

You are provided with solid C7. Carry out the tests below and record your observations and inferences in the spaces provided.

(a)Place half end full of solid C7 in a dry test tube and heat gently first and then strongly
(b)Place the remainder of solid C7 in a boiling tube and add about 10cm3 of distilled water. Shake well. Divide the solution into 4 portions of about 2cm3 each for the tests below.
(c)To the 1st portion, add a few drops dilute Sulphuric (vi) acid
(d)To the 2nd Portion, add aqueous sodium hydroxide dropwise till in excess
(d)To the 3rd portion add two drops of aqueous lead (ii) nitrate

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.

T0T0

B.T

STUDENT LABORATORY WORKBOOK

Procedure	Observations	Inferences
(a) Heating Solid C7 gently then strongly
(b) Solid C7 in boiling tube + 10cm3 distilled water
(c) 1st portion + few drops of H2SO4
(d) 2nd portion + NaOH dropwise tll in excess
(e) 3rd portion + Pb(NO3)2Y

OFFICIAL MARKING SCHEME & EXPECTED RESPONSES

Procedure	Observations	Inferences
(a) Heating Solid C7 gently then strongly	Colourless liquid forms on the cooler parts of the test tube/Colourless vapour condenses on the cooler parts of the test tube. (1 mark)	Hydrated salt/solid C7 contains water of crystallization (1mark)
(b) Solid C7 in boiling tube + 10cm3 distilled water	Solid dissolves to form a colourless solution (1 Mark)	Soluble salt/soluble compound Cu2+, Fe2+, Fe3+ absent (1 mark)
(c) 1st portion + few drops of H2SO4	Whie precipitate (1 mark)	Ca2+, Pb2+, Ba2+ present (1 mark)
2. (d) Portion 3 + NaOH dropwise till in excess	White precipitate insoluble in excess sodium hydroxide (1 mark)	Ca2+ present (1 mark)
(e) 3rd portion + Pb(NO3)2	White precipitate (1 mark)	Cl- present SO4 2-, SO3 2-, CO3 2- is contradictory because SO4 2-, SO3 2-, CO3 2- are insoluble
		*Identity of solid C7: Calcium Chloride - CaCl2*

Sample Test 18