The
magnesium metal is highly reactive and can ignite in contact with moisture or
even air. The skin is usually covering in moisture, so the contact with it may cause
a reaction that can produce irritation, lesions and even burns.
Crucible
tongs are mandatory to handle hot crucibles to avoid skin burns and accidents
during experimental procedures. Crucible tongs work with the crucible; their shape
was designed to firmly hold it to avoid spills.
Touching the magnesium metal can actually contaminate it
and bring with it impurities which may not be removed by heating. So this leads
to error in weighing.
There are two reasons not to touch the crucible tong with
bare hands:
1. The crucible tong is used during firing so it is
extremely hot and may burn your hands
2. Any impurities in your hand may contaminate the tong
hence leading to error just like the case for the magnesium metal
Because 17,190 yrs divided by the amount of years it takes for a half-life to occur is 3. So 3 half life’s happen, so you divide 144/2 once, equaling 72. You divide 72/2 again (another half-life) and you get 36. You then calculate the third half life by dividing 36/2 which equals 18 grams.