LEARNING AND TEACHING RESOURCES ON PRACTICAL FOR
CHEMISTRY AND COMBINED SCIENCE (CHEMISTRY PART) CURRICULA
Sophia SL Cheng
Science Education Section, EDB
Learning and Teaching Resources for Senior Secondary Chemistry
and Combined Science (Chemistry Part)
(http://cd1.edb.hkedcity.net/cd/science/chemistry/resources_by_topics/i
ndex.html)
INTEGRATE SBA WITH LEARNING AND TEACHING
Example 1
Pre-lab assignment +
Volumetric analysis using HCl(aq) and Na2CO3(aq)
Topic XV Analytical Chemistry
Students should learn Students should be able to
d. Instrumental analytical methods
basic principles and applications of
colorimetry
understand the basic principles deployed in
the instrumental analytical methods, viz.
colorimetry, IR spectroscopy and mass
spectrometry
construct a calibration curve by measuring
absorbance of standard solutions
determine the concentration of a solution
using a calibration curve
2016 HKDSE Paper II Q3(b)
Topic XV(d) Instrumental
analytical methods
Objective
• To determine the amount of copper in a brass sample
Chemical reactions
3Zn + 2NO3- + 8H+ 3Zn2+ + 2NO + 4H2O
3Cu + 2NO3- + 8H+ 3Cu2+ + 2NO + 4H2O
2NO + O2 2NO2
The determination of copper in brass
The determination of copper in brass
The determination of copper in brass
Relative absorbance = log10(V0 / Vs)
where V0 is the voltage reading with a cuvette containing deionized water
Vs is the voltage reading with a sample in the cuvette
Deionised water
0.1 mol dm-3 CuSO4(aq)
0.2 mol dm-3 CuSO4(aq)
0.3 mol dm-3 CuSO4(aq)
0.4 mol dm-3
CuSO4(aq) 0.5 mol dm-3 CuSO4(aq)
Sample solution
Voltage reading / V
0.822 0.794 0.766 0.736 0.705 0.649 0.735
Relative absorbance
log10(0.822/ 0.794) = 0.0151
0.0306 0.0480 0.0667 0.103 0.0486
The determination of copper in brass
Conc. of sample Cu2+(aq) = 0.281 M Mass of Cu in brass solution = 0.178 g
% by mass of Cu in brass sample = 59.3%
Topic VIII Chemical Reactions and Energy
Students should learn Students should be able to
b. Standard enthalpy changes of
reactions
explain and use the terms: enthalpy change
of reaction and standard conditions, with
particular reference to neutralisation,
formation and combustion
carry out experimental determination of
enthalpy changes using simple calorimetric
method
calculate enthalpy changes from
experimental results
2019 HKDSE Paper IB Q8
Topic VIII(b) Standard enthalpy
changes of reactions
Determining the Stoichiometry of Reaction Between ClO- and S2O32-/OH-
Objective
To determine the stoichiometry of a chemical reaction
_____ClO- + _____S2O32- + _____OH- _____Cl- +_____SO4
2- +_____H2O
Chemicals
Solution A: 0.5 M sodium hypochlorite, 55 mL
Solution B: 0.5 M sodium thiosulphate in 0.2 M sodium hydroxide, 55 mL
For every 1 mole of Na2S2O3 that reacts, 4 moles of NaClO are needed. 4 ClO- + S2O3
2- + 2 OH- 4 Cl- + 2 SO42- + H2O
Sample data
Volumetric Analysis: “Low Sodium” Salt Substitutes
◦ To determine the proportions of potassium
chloride and sodium chloride in low-sodium salt
substitutes using a titration procedure
◦ Mohr Method
NaCl(aq) + AgNO3(aq) NaNO3(aq) + AgCl(s)
KCl(aq) + AgNO3(aq) KNO3(aq) + AgCl(s)
◦ [End-Point Reaction]
2Ag+(aq) + CrO42-(aq) Ag2CrO4(s)
red ppt
At the beginning AgCl is being formed
during titration
Ag2CrO4(s) is formed at
the end point
Data analysis
From the titration results, the no. of moles of Cl-(aq) = 0.0149 mol
Mass of the salt sample = 1.00 g
Let mass of NaCl be x, then mass of KCl = 1.00 – x
No. of moles of Cl- from NaCl = x
58.5
No. of moles of Cl- from KCl = 1.00 − x
74.5
Total no. of moles of Cl- = x
58.5 +
1.00 − x74.5
= 0.0149
x = 0.403
Therefore, % of NaCl by mass = 40.3%
% of KCl by mass = 59.7%
Some more practical activities
Typical reactions of various functional groups (Topic XI c)
◦ Reduction of Vanillin with Sodium Borohydride
Rate of Reaction (Topic IX b)
◦ Reaction of Phenolphthalein in NaOH solution (with the
use of datalogger)
Microscopic World II (Topic VI b)
◦ Evaporation and Intermolecular Attractions
Analytical Chemistry (Topic XV b)
◦ Thin-layer Chromatography of Painkillers
http://www.hkeaa.edu.hk/tc/sba/sub_info_sba/dse_subject.html?7&4
YouTube Channel:
https://qrgo.page.link/sKAf4
http://minisite.proj.hkedcity.net/safetyonline/eng/index.html
References and resources for Chemistry, Science Education, EDB
(http://www.edb.gov.hk/en/curriculum-development/kla/science-
edu/ref-and-resources/chemistry.html)
Curriculum Documents, Science Education, EDB
(http://www.edb.gov.hk/en/curriculum-development/kla/science-
edu/curriculum-documents.html)
Course ID Course title Date & Time
CDI020200409 Understanding and Interpreting the
Chemistry and Combined Science
(Chemistry Part) Curricula (Re-run)
28/10/2019
2:00 p.m. – 5:00 p.m.
CDI020191377 Course for Laboratory Technicians:
Understanding and Interpreting the
Chemistry and Combined Science
(Chemistry Part) Curricula (New)
15/11/2019
2:30 p.m. – 4:30 p.m.
CDI020200460 Course for New Teachers – Promoting
the Quality of Chemistry Learning with
Effective Teaching Strategies and
Learning Activities (New)
29/11/2019
2:00 p.m. – 5:00 p.m.
Training programme (Oct/Nov 2019)
Contact information
Sophia Cheng
Tel: 3698 3439
Email: [email protected]
Tim Tse
Tel: 3698 3438
Email: [email protected]
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