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Harrizon [31]
3 years ago
12

What was helium used for in the past?

Chemistry
2 answers:
yawa3891 [41]3 years ago
6 0
Helium used to be used in hot air balloons.  Then, when the Hindenburg exploded, annexed file, they realized that hydrogen was not only lighter, but it also was less flammable.  

Otrada [13]3 years ago
3 0

Hot air balloons. They have a little hot plate/fire or whatever and they used, and that made the helium rise, thus rising the balloon.
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Hypothesis

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5 0
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pochemuha
   The energy change  if 84.0 g   of CaO  react  with  excess  water is  98KJ of heat is released.

calculation
heat  =  number of moles  x  delta H

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first find the number of  moles  of  CaO reacted

moles = mass/molar mass
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Heat is therefore =  1.5 moles  x -65.2 = - 97.8 Kj = -98 Kj

  since  sign is  negative  the   energy  is released 

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