Question

9.
Correct option for an endothermic gaseous reaction
A + B 3C will be
(1) AH > 0; AS <0 (2) AH = 0; AS > 0
(3) AH > 0; AS > 0 (4) AS = 0; AS < 0​

Answer 1

Answer: The correct answer is Option 3.

Explanation:

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 $(\Delta H)$ 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 $(\Delta H)$ comes out to be negative.

For the given chemical equation:

$A(g)+B(g)\rightarrow 3C(g)$

The value of $\Delta S$ depends on the change of number of moles.

If the change in number of moles is positive, the value of $\Delta S$ is positive and if the change in number of moles is negative, the value of $\Delta S$ is negative

$\Delta n_g=(3-2)=+1$

As, the change in number of moles of gases is coming out to be +1, the $\Delta S$ will be positive.

Therefore, for the given reaction, conditions are:

• $\Delta H>0$
• $\Delta S>0$

Hence, the correct answer is Option 3.

Answer 2

Answer:

option 3

Explanation:

please check the picture