RELATIVE ATOMIC MASS/RELATIVE ABUNDANCE QUESTIONS

Question 1:
Calculate the relative atomic mass of silver if it occurs naturally as 51.84% silver-107 and 48.18% silver-109.

Solution:
Relative atomic mass = 0.5184 (107) + 0.4816 (109)
Relative atomic mass = 107.96

Question 2:
Calculate the relative abundance of each isotope of copper if it consists of two isotopes, copper-63 and copper-65. Its relative atomic mass is 63.62.

Solution:
Let Abundance of copper-63 = x
Then, Abundance of copper-65 = 1-x

Relative atomic mass = 63x + 65(1-x)
                                      63x + 65(1-x) = 63.62
                                       x = 0.69
That is, 69% of copper-63 and 31% of copper-65

THE MASS SPECTROMETER

The mass spectrometer is an instrument used for analyzing samples of elements and compounds. It consists of six basic stages: Injection, Vaporization,  Ionization, Acceleration, Deflection, and  Detection.

Click to view a diagram of the mass spectrometer.

• The sample is injected into the instrument.
•  It may be vaporized by heating. 
• The vaporized sample is then passed into an ionizing beam of electrons which knock electrons off the sample to create positive ions.
• These positive ions are then accelerated by some electrostatically charged plates into a magnetic field.
• The magnetic field then deflects the particles according to their mass/charge ratio.
• The deflected ions then arrive at the detector.

You can test yourself on the atomiser by clicking this link. It is a timed quiz.