Question

A chemist measures the energy change ?H during the following reaction:

Answer 1

Answer:

(A) endothermic

(A) Yes, absorbed

Explanation:

Let's consider the following thermochemical equation.

2 Fe₂O₃(s) ⇒ 4 FeO(s) + O₂(g)  ΔH = 560 kJ

Since ΔH > 0, the reaction is endothermic.

We can establish the following relations:

• 560 kJ are absorbed when 2 moles of Fe₂O₃ react.
• The molar mass of Fe₂O₃ is 160 g/mol.

Suppose 66.6 g of Fe₂O₃ react. The heat absorbed is:

$66.6g.\frac{1mol}{160g} .\frac{560kJ}{2mol} =117kJ$