Chemical Analysis Flashcards
1
Q
Cations
A
Positive ions
2
Q
Precipitate
A
An insoluble solid formed from a solution
3
Q
Practical: Flame tests colours
A
- Dip the wire into HCL to clean any contaminants
- Dip the wire into a named metal salt solution and hold the wire in a blue flame
- Record the colour of the flame in a results table
- Repeat for all the metal salt solutions
4
Q
Aqueous ion : Lithium
A
Crimson
5
Q
Aqueous ion : Sodium
A
Yellow
6
Q
Aqueous ion : Potassium
A
Lilac
7
Q
Aqueous ion : Calcium
A
Orange-red
8
Q
Aqueous ion : Copper
A
Green
9
Q
Limitations of the cation flame tests
A
. The flame test only works with samples with single ions
. If the sample contains more than one ion then one or more colours may be masked by the other
10
Q
Practical: Precipitation reactions
A
- Pour a little of a metal salt into a test tube at a 1cm depth
- Add a few drops of dilute sodium hydroxide to the test tube using a pipette
- Observe and record the colour of the precipitate formed into a results table
- Repeat for each metal salt solution
11
Q
Metal ion : Cu 2+
A
Blue
12
Q
Metal ion : Fe 2+
A
Green
13
Q
Metal ion : Fe 3+
A
Brown
14
Q
Metal ion : Al 3+
A
White
15
Q
Metal ion : Ca 2+
A
White
