Paramagnetism Activity
Background:
When a magnetic field is introduced some materials tend to become magnetized. The
introduction of the magnetic field causes lone electrons closest to the magnetic field to
become oriented in the same direction thus creating a slight attraction towards the
magnetic field. This type of substance is considered paramagnetic. When the magnetic
field is removed the electrons become disorganized and are no longer oriented in the
same direction.
Atoms that are repelled by an external magnetic field are diamagnetic. Atoms attracted
to an external magnetic field are paramagnetic. A strong neodymium magnet placed on
a balance can be used to test for paramagnetism. The magnet will be attracted to
paramagnetic compounds and cause the mass reading to decrease. Diamagnetic
substances will repel the magnet and cause the mass reading to increase. The greater
the number of unpaired electrons, the greater the paramagnetism per mole of
substance.
Purpose: To examine the effect that unpaired electrons have on the strength of the
paramagnetism of a metal salts.
Materials:
6 test tubes
3.00g samples of sulfate compounds
Electronic balance
Pre-lab:
Complete the following table:
Electron
Ionic
Metal Configuration
Compound
Ion
of ion
(3.00g)
Aluminum
Sulfate
Manganese (II)
Sulfate
Copper (II)
Sulfate
Pentahydrate
Magnesium
Sulfate
Zinc Sulfate
Sodium
Sulfate
Retort stand
Neodynium magnet
Retort clamp
Number
of
unpaired
electrons
Prediction
Molar mass
Paramagnetic
of ionic
/
compound
Diamagnetic
Number of
moles of
ionic
compound
Procedure:
1. 3.00g masses of ionic compounds composed of alkaline earth and transition
metal ions were placed into large, stoppered test tubes.
2. The test tubes were lowered to the same height above a balance that has been
zeroed with a neodymium magnet placed on the scale.
3. Mass changes were recorded as the test tube is lowered toward the magnet.
Observations:
Ionic
Compound
(3.00 g)
Aluminum
Sulfate
Manganese
(II) Sulfate
Copper (II)
Sulfate
Pentahydrate
Magnesium
Sulfate
# unpaired
electrons
Observed
∆Mass (g)
∆Mass/mole
Zinc Sulfate
Sodium
Sulfate
Analysis:
1. What variables were controlled in this investigation?
2. Which solids were paramagnetic?
3. Explain why some solids cause a zero change in the magnet’s mass while others
cause a negative change in the magnet’s mass.
4. Plot a graph of the number of unpaired electrons
versus the change in mass per mole. Draw a line of
best fit.