THIS USER ASKED 👇

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.

THIS IS THE BEST ANSWER 👇

Answer: Only option A shows  Delta H =  Delta E.

Explanation:

Formula used:

 Delta H =  Delta E +  Delta n_gRT

 Delta H. change in enthalpy

 Delta E. change in internal energy

 Delta n_g change of moles

R = gas constant = 8.314 J / mol.K.

T = temperature

By the question,  Delta H =  Delta E. when value  Delta n_gRT there will be zero.

Now we have the value of  Delta n_gRT for the following cases.

(A) 2HI (g)  rightarrow H_2 (g) + I_2 (g) pushing the atmosphere.

In this case:

 Delta n_g change of moles

Mole change = Number of moles on the product side – Number of moles on the reactant side

By reaction:

Mole change = (1 + 1) – 2 = 2 – 2 = 0 mole

That means, value  Delta n_gRT = 0

So in this process  Delta H =  Delta E.

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

In this case:

 Delta n_g change of moles

That means, value  Delta n_gRT ≠ 0

So in this process  Delta H  neq  Delta E.

(C) H_2O (l)  rightarrow H_2O (g) at 100 ° C at atmospheric pressure.

In this case:

Mole change = Number of moles on the product side – Number of moles on the reactant side

By reaction:

Mole change = 1 – 0 = 1 mole

 Delta n_g change of moles

That means, value  Delta n_gRT ≠ 0

So in this process  Delta H  neq  Delta E.

(D) CaCO_3 (s)  rightarrow CaO (s) + CO_2 (g) at 800 ° C at atmospheric pressure.

In this case:

Mole change = Number of moles on the product side – Number of moles on the reactant side

By reaction:

Mole change = 1 – 0 = 1 mole

 Delta n_g change of moles

That means, value  Delta n_gRT ≠ 0

So in this process  Delta H  neq  Delta E.

(E) CO_2 (s)  rightarrow CO_2 (g) pushing the atmosphere.

In this case:

Mole change = Number of moles on the product side – Number of moles on the reactant side

By reaction:

Mole change = 1 – 0 = 1 mole

 Delta n_g change of moles

That means, value  Delta n_gRT ≠ 0

So in this process  Delta H  neq  Delta E.

Accordingly, we are of the view that only option A is shown for this  Delta H =  Delta E.