1. A chemist measures the energy change ΔH during the following reaction:
2Fe_2O_3 (s) ------> 4FeO (s) _O_2 (g) ΔH = 560.kJ
Use the information to answer the following questions.
This reaction is:
a. endothermic.
b. exothermic.
2. Suppose 67.6 g of Fe_2O_3, react. Will any heat be released or absorbed?
a. Yes, absorbed.
b. Yes, released.
c. No.
If you said heat will be released or absorbed in the second part of this question, calculate how much heat will be released or absorbed.
Be sure your answer has the correct number of significant digits.

Endothermic reactions are defined as the reactions in which energy of products is more than the energy of the reactants. In these reactions, energy is absorbed by the system. The total enthalpy of the reaction [tex](\Delta H)[/tex] comes out to be positive.

Exothermic reactions are defined as the reactions in which energy of reactants is more than the energy of the products. In these reactions, energy is released by the system. The total enthalpy of the reaction [tex](\Delta H)[/tex] comes out to be negative.

For 1:

The given chemical reaction:

[tex]2Fe_2O_3(s)\rightarrow 4FeO(s)+O_2(g);\Delta H=560.kJ[/tex]

As, the enthalpy change of the reaction is positive, the reaction is considered as endothermic reaction.

For 2:

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

Given mass of iron (III) oxide = 67.6 g

Molar mass of iron (III) oxide = 159.7 g/mol

Putting values in above equation, we get:

[tex]\text{Moles of }Fe_2O_3=\frac{67.6g}{159.7g/mol}=0.423mol[/tex]

By Stoichiometry of the reaction:

When 2 moles of iron (III) oxide is reacted, the heat absorbed is 560 kJ

So, when 0.423 moles of iron (III) oxide will react, the heat absorbed will be = [tex]\frac{560}{2}\times 0.423=118.44kJ[/tex]

Hence, yes, 118.44 kJ of heat is absorbed.