In which one of the following processes is δh = δe? a. 2hi(g) => h2(g) + i2(g) at atmospheric pressure. b. two moles of ammonia gas are cooled from 325 ? °c to 300 °c at 1.2 atm. c. h2o(l) => h2o(g) at 100 °c at atmospheric pressure. d. caco3(s) => cao(s) + co2(g) at 800 °c at atmospheric pressure. e. co2(s) => co2(g) at atmospheric pressure.

Answer : Only option A shows

Explanation :

Formula used :

= change in enthalpy

= change in internal energy

= change in moles

R = gas constant = 8.314 J/mol.K

T = temperature

According to the question, when the value of will be zero.

Now we have to determine the value of for the following cases.

(A) at atmospheric pressure.

In this case:

= change in moles

Change in moles = Number of moles of product side - Number of moles of reactant side

According to the reaction:

Change in moles = (1+1) - 2 = 2 - 2 = 0 mole

That means, value of = 0

So, in this process

(B) Two moles of ammonia gas are cooled from 325 °C to 300 °C at 1.2 atm.

In this case:

= change in moles = 2

That means, value of ≠ 0

So, in this process

(C) at 100 °C at atmospheric pressure.

In this case:

Change in moles = Number of moles of product side - Number of moles of reactant side

According to the reaction:

Change in moles = 1 - 0 = 1 mole

= change in moles = 1

That means, value of ≠ 0

So, in this process

(D) at 800 °C at atmospheric pressure.

In this case:

Change in moles = Number of moles of product side - Number of moles of reactant side

According to the reaction:

Change in moles = 1 - 0 = 1 mole

= change in moles = 1

That means, value of ≠ 0

So, in this process

(E) at atmospheric pressure.

In this case:

Change in moles = Number of moles of product side - Number of moles of reactant side

According to the reaction:

Change in moles = 1 - 0 = 1 mole

= change in moles = 1

That means, value of ≠ 0

So, in this process

Hence, from this we conclude that, only option A shows