1
Q
Flame Test
Barium - Ba2+
A
Apple green
2
Q
Flame Test
calcium - ca2+
A
brick red /orange
3
Q
Flame Test
Lead - Pb2+
A
Grey Blue
4
Q
Flame Test
Copper - Cu2+
A
Green
5
Q
Flame Test
Fe2+ / Fe3+
A
orange-brown
6
Q
Flame Test
Na+
A
yellow
7
Q
Flame Test
Li+
A
Red-Pink
8
Q
Flame Test
Sr2+
A
Crimson
9
Q
Flame Test
k+
A
Lilac
10
Q
Flame Test
Mg2+ and Ag+
A
No characteristic colour
11
Q
Flame Test
Limitations of FT
A
- can only be used for some metal cations
- destructive test (alters or consumes the sample being tested)
- different oxidisation states cannot be determine, such as iron (ii) or iron (iii)
- inteference can be caused by other metal ions (e.g. If your sample contains more than one type of metal ion, the flame colours can overlap, mask, or change each other, making it hard to identify the individual ions clearly.)
12
Q
Cation Analysis
There are 3 main methods for cation analysis
A
- Flame Test
- Precipitation Analysis
- Complexation Reactions
13
Q
Flame Test
Principle of flame test
A
- Electrons are energised or excited to a higher energy state by absorbing the heat energy from the flame. Since this state is unstable, the electrons will drop down to their stable state emitting light energy.
- Due to the unique electron configuration of each element, the energy absorbed and frequency/wavelength of light emitted varies between each element.
- Traditionally, only metals are able to be detected as they emit wavelengths in the visible light range of the EMR spectrum.
14
Q
Complexation
Complexation Reaction
A
Complexation reactions involve the formation of a complex ion where one or more small molecules or ions attach themselves to a central cation.
HSC Chemistry
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