Test Procedure

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

(a) Divide solid E into halves. Place one half of solid E in a clean dry test tube. Heat it gently then strongly.
(b) Place the other half of solid E in a boiling tube. Add about 10cm3 of distilled water to dissolve and divide into 3 portions.
- (i) To about 1cm3 of solution, add 2cm3 of sodium hydroxide dropwise until in excess.
- (ii) Place 1cm3 of solution in test-tube and add 2-3 drops of 2M Sulphuric acid
- (iii) To about 1cm3 of solution, add 4-5 drops of lead (ii) nitrate solution and heat to boiling

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) Divided solid E into halves. Placed one half of solid E in a clean dry test tube + heated gently then strongly
b (i) To about 1cm3 of the solution + NaOH dropwise until in excess
(ii) 1cm3 of the solution + 2 to 3 drops of 2M H2SO4
(iii) 1cm3 of the solution + 4-5 drops of Pb(NO3)2

OFFICIAL MARKING SCHEME & EXPECTED RESPONSES

Procedure	Observations	Inferences
(a) Divided solid E into halves. Placed one half of solid E in a clean dry test tube + heated 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) (i) To about 1cm3 of the solution + NaOH dropwise until in excess	White precipitate insoluble in excess (1 Mark)	Ca2+, Mg2+ present (1 mark)
(ii) 1cm3 of the solution + 2 to 3 drops of 2M H2SO4	Dense Whie precipitate (1 mark)	Ca2+ present (1 mark)
(iii) 1cm3 of the solution + 4-5 drops of Pb(NO3)2	White precipitate dissolves on boiling (1 mark)	Cl- present (1 mark)
		*Identity of solid E: Calcium Chloride - CaCl2*

Sample Test 12