2 Al + Fe2O3 = Al2O3 + 2 Fe + 850 kJ How many kJ are produced by 2 moles of Fe2O3? *

1700 kj

Explanation:

The given reaction is exothermic reaction.

Exothermic reaction:

The type of reactions in which energy is released are called exothermic reactions.

In this type of reaction energy needed to break the bonds are less than the energy released during the bond formation.

For example:

Chemical equation:

C + O₂   →  CO₂

ΔH = -393 Kj/mol

it can be written as,

C + O₂   →  CO₂ + 393 Kj/mol

Chemical equation:

2Al + Fe₂O₃     →    Al₂O₃ + 2Fe + 850 Kj

when one mole of Fe₂O₃  react 850 kj energy is produced.

when 2 moles react,

2 × 850 kj = 1700 kj

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"