C12.6 Instrumental Techniques

Question 1

Advantages of instrumental techniques? (3)

Answer 1

• Highly accurate and sensitive
• Quicker
• Enable very small samples to be tested

Question 2

Disadvantages of instrumental techniques? (3)

Answer 2

• Equipment is usually very expensive
• Requires special training
• Gives results that can often be interpreted only by comparison

Question 3

How does flame emission spectography work?

Answer 3

• Samples are heated in a flame
• The energy provided gives the electrons more kinetic energy, making them jump into higher energy shells/levels
• When they fall back into the lower energy shell/level, energy is released as light energy = flame colour + flame test
• The machine then analyses the light in the spectroscope; each type of metal ion gives off its own characteristic pattern of radiation = line spectrum
• The line spectrum can then be used to identify the metal ion.