Name:
Class:
(
)
Date:
S5 Chemistry
SBA Experiment
Qualitative Analysis
Objective:
z To distinguish five colourless solutions from each other
Apparatus and Chemicals
z test tubes in rack
z droppers
z protective gloves
z wash bottle
z distilled water
z
z
z
z
z
dilute
dilute
dilute
dilute
dilute
(2 mol dm–3)
HNO3(aq)
CaCl2(aq)
(2 mol dm–3)
NaCl(aq)
(2 mol dm–3)
Na2CO3(aq) (1 mol dm–3)
Pb(NO3)2(aq) (0.2 mol dm–3)
Safety:
1. Avoid direct contact with chemicals. Safety glasses and protective gloves must be worn.
2. Dispose of chemical wastes and excess materials according to your teacher’s instruction.
Task:
z In this investigation, there are five test tubes randomly labelled as A, B, C, D and E. Each of
the test tubes contains one of the following colourless solutions. Mix the solutions and record
all your observations in the results table given.
HNO3(aq), CaCl2(aq), NaCl(aq), Na2CO3(aq), Pb(NO3)2(aq)
Procedure:
1. Use 2 cm3 of each reagent for all tests.
2. After the addition of any reagent, shake the test tube gently to facilitate the mixing.
3. Make careful observations and record all observations immediately after each test.
Assessment Criteria:
Marks
10 − 9
8−6
5−3
2−1
Remarks
z
z
z
z
z
z
z
z
z
Nearly all observations are accurately described.
The five solutions are logically distinguished.
Safety procedures have been observed.
Some observations are accurately described.
At least three of the solutions are logically distinguished.
Safety procedures have been observed.
Some observations are accurately described.
At least two of the solutions is logically distinguished.
Safety procedures have been observed.
z
z
Some observations are accurately described.
At least one of the solutions is distinguished.
Teacher’s Remark (if any):
z During the experiment, students’ practical skills can also be assessed.
z Students should be reminded that marks may be adjusted if unsafe practice is noted.
S5 Chemistry/SBA Experiment/Qualitative Analysis (Set B)
Name:
Class:
Results:
Observation
(
B
)
Date:
C
Marks:
D
/10
E
A
B
―
C
―
―
D
―
―
―
From your observations, distinguish what A, B, C and D are. Explain your distinguishing process.
Solution A
Solution B
Solution C
S5 Chemistry/SBA Experiment/Qualitative Analysis (Set B)
Solution D
Solution E
Results:
Observation
B
C
D
E
A
No
observable
change
B
―
No
observable
change
White
precipitate
formed
White
precipitate
formed
White
precipitate
formed
No
observable
change
No
observable
change
C
―
―
White
precipitate
formed
Colourless gas
bubbles evolved
D
―
―
―
No
observable
change
From your observations, distinguish what A, B, C and D are. Explain your distinguishing process.
C reacts with E to give a colourless gas, C and E may be Na2CO3(aq) and HNO3(aq).
i.e. Na2CO3(aq) + 2HNO3(aq) → 2NaNO3(aq) + CO2(g) + H2O(l)
E does not give any significant observable change when mixes with A, B and D.
It is just like that HNO3(aq) would not react with CaCl2(aq), NaCl(aq)and Pb(NO3)2(aq).
Therefore, E is HNO3(aq) and hence C is Na2CO3(aq).
C (Na2CO3(aq)) does not react with A,
A should be NaCl(aq).
C (Na2CO3) reacts with B and D to give white precipitate.
B and D may be CaCl2(aq) or Pb(NO3)2(aq).
i.e. Na2CO3(aq) + CaCl2(aq) → 2NaCl(aq) + CaCO3(s)
Na2CO3(aq) + Pb(NO3)2(aq) → 2NaNO3(aq) + PbCO3(s)
B (CaCl2(aq) or Pb(NO3)2(aq)) does not react with A (NaCl(aq)),
B should be CaCl2(aq).
D (CaCl2(aq) or Pb(NO3)2(aq)) reacts with A (NaCl(aq)) to give a white precipitate,
D should be Pb(NO3)2(aq).
i.e. Pb(NO3)2(aq) + 2NaCl(aq) → 2NaNO3(aq) + PbCl2(s)
Solution A
Solution B
Solution C
Solution D
Solution E
NaCl(aq)
CaCl2(aq)
Na2CO3(aq)
Pb(NO3)2(aq)
HNO3(aq)
S5 Chemistry/SBA Experiment/Qualitative Analysis (Set B)