1. 1. Introducing Chemical Analysis
• Qualitative analysis is used to identify chemical
species (elements, compounds and ions) present in
an unknown substance.
• Quantitative/Volumetric analysis is used to
determine the amount or concentration of these
chemical species (elements, compounds and ions)
present.

2. 2. Use of Physical Tests to Identify
Substances
• Additional tests are needed to identify a substance:
– Colour
– Smell
– Solubility in water
– pH
Calcium compounds Solid copper(II) Aqueous iron(III) ions are
are white. sulfate is blue. yellow-orange.

3. 3. Identification of Ions
Testing for Cations
• Cations are positively-charged ions.
• Aqueous sodium hydroxide and aqueous
ammonia can be used to identify cations in
salts.
• Cations can be identified:
– From the colour of the precipitate,
and
A precipitate of zinc
– If the precipitate dissolves in excess hydroxide
alkali.
Identifying an ammonium
compound.

4. Test for ammonium ions, NH4+
http://www.youtube.com/watch?v=b28pw1q2qdo&feature=related
Test for calcium ions, Ca2+
http://www.youtube.com/watch?v=AvnLlWVOa44&feature=related
Test for lead(II) ions, Pb2+
http://www.youtube.com/watch?v=CPnG4OKxgEQ&feature=related
Test for zinc ions, Zn2+
http://www.youtube.com/watch?v=JjPNDnoxYN4&feature=related
Test for aluminium ions, Al3+
http://www.youtube.com/watch?v=D3s-_0xUS-k&feature=related
Test for copper(II) ions, Cu2+
http://www.youtube.com/watch?v=KLGRf4AdKQM&feature=related
Test for iron(II) ions, Fe2+
http://www.youtube.com/watch?v=bivr2CzlTF4&feature=related
Test for iron(III) ions, Fe3+
http://www.youtube.com/watch?v=gj7ju9wRtdY&feature=related

5. Using aqueous sodium hydroxide to distinguish:
sodium, potassium and ammonium ions
http://www.youtube.com/watch?v=kAnEzELqfjQ&feature=youtu.be
calcium, aluminium, lead and zinc ions
http://www.youtube.com/watch?v=cxOjcN_G4zg&feature=youtu.be
iron(II), iron(III) and copper(II) ions
http://www.youtube.com/watch?v=iKQ-uPqx4n4&feature=youtu.be
Using aqueous ammonia to distinguish:
sodium, potassium and calcium ions
http://www.youtube.com/watch?v=G0lYQH4OVqA&feature=youtu.be
aluminium, lead(II) and zinc ions
http://www.youtube.com/watch?v=UjLBaKZZ_2k&feature=youtu.be
iron(II), iron(III) and copper(II) ions
http://www.youtube.com/watch?v=xaRPwuAOqpc&feature=youtu.be

6. 3. Identification of Ions
Testing for Cations

7. 3. Identification of Ions
Testing for Cations
• Cations can be identified with
aqueous sodium hydroxide.

8. 3. Identification of Ions
Testing for Cations
• Cations can be identified with
ammonia solution.

9. 3. Identification of Ions
Testing for Anions
• Anions are negatively-charged ions.
• Tests for carbonate, chloride, iodide and sulfate often involves precipitation
reactions.

10. 3. Identification of Ions
Testing for Anions
Testing for two anions: (a) carbonate and (b)
iodide

11. Test for carbonate ions, CO32−
http://www.youtube.com/watch?v=197iyKaRhtA&feature=related
Test for sulfate ions, SO42−
http://www.youtube.com/watch?v=oEXYjqSUg4g&feature=related
Test for chloride ions, Cl−
http://www.youtube.com/watch?v=vcQXdeL-juM&feature=related
Test for iodide ions, I−
http://www.youtube.com/watch?v=lw5VUL4-O8M&feature=related
Test for nitrate ions, NO3−
http://www.youtube.com/watch?v=NyB5XfbSwSo&feature=channel

12. Test for halides (Cl−, I−) using dilute nitric acid and
aqueous silver nitrate
http://www.youtube.com/watch?v=C2Lh48zAyqk&feature=youtu.be
Test for halides (Cl−, I− ) using dilute nitric acid and
aqueous lead(II) nitrate
http://www.youtube.com/watch?v=xAsHDFfCR14&feature=youtu.be

13. 4. Testing for Gases and Water
Testing for Gases
sulfite +
acid mixture
Testing for sulfur
dioxide gas

14. 4. Testing for Gases and Water
Testing for Water
• Test liquid with a piece of blue anhydrous cobalt(II)
chloride paper.
• Water turns blue anhydrous cobalt(II) chloride paper
pink.
Test for water