Question

Which of the following statements concerning the reaction shown below are true? P4 (s) + 3O2 (g) → P4O6 (s) ∆H = -1640 kJ I. heat is absorbed II. heat is released III. rxn is exothermic IV. rxn is endothermic V. products have higher enthalpy content than reactants VI. reactants have higher enthalpy content than products

Answer 1

Answer: ii) heat is released

iii) reaction is exothermic

vi) reactants have higher enthalpy content than products

Explanation:

$P_4(s)+3O_2(g)\rightarrow P_4O_6(s)$  $\Delta H=-1640kJ$

Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and $\Delta H$ for the reaction comes out to be negative.

Endothermic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and $\Delta H$ for the reaction comes out to be positive.

As heat change is negative, the reaction is exothermic. Energy of reactants is more as compared to energy of products and thus energy is released.

Answer 2

Heat is released is true