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Anni [7]
3 years ago
6

What is the energy change if 84.0 g of calcium oxide (CaO) reacts with excess water in the following reaction?

Chemistry
1 answer:
pochemuha3 years ago
6 0
   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

delta H = - 65.2  Kj/mol

first find the number of  moles  of  CaO reacted

moles = mass/molar mass
the molar mass  of CaO =  40 +  16=  56 g/mol
mass = 84 g
moles therefore = 84 g/56 g/mol =1.5 moles

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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<u>Answer:</u> The mass of methanol that must be burned is 24.34 grams

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By Stoichiometry of the reaction:

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Putting values in above equation, we get:

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