Question

Enter your answer in the provided box. Consider the reaction H2(g) + Cl2(g) → 2HCl(g)ΔH = −184.6 kJ / mol If 2.00 moles of H2 react with 2.00 moles of Cl2 to form HCl, what is ΔU (in kJ) for this reaction at 1.0 atm and 25°C? Assume the reaction goes to completion.

Answer 1

Answer : The value of $\Delta E$ of the reaction is, -369.2 KJ

Explanation :

Formula used :

$\Delta E=\Delta H-\Delta n_g\times RT$

where,

$\Delta E$ = internal energy of the reaction = ?

$\Delta H$ = enthalpy of the reaction = -184.6 KJ/mole = -184600 J/mole

The balanced chemical reaction is,

$H_2(g)+Cl_2(g)\rightarrow 2HCl(g)$

when the moles of $H_2\text{ and }Cl_2$ are 2 moles then the reaction will be,

$2H_2(g)+2Cl_2(g)\rightarrow 4HCl(g)$

From the given balanced chemical reaction we conclude that,

$\Delta n_g$ = change in the moles of the reaction = Moles of product - Moles of reactant = 4 - 4 = 0 mole

R = gas constant = 8.314 J/mole.K

T = temperature = $25^oC=273+25=298K$

Now put all the given values in the above formula, we get:

$\Delta E=(-184600J/mole\times 2mole)-(0mole\times 8.314J/mole.K\times 298K)$

$\Delta E=-369200J$

$\Delta E=-369.2KJ$

Therefore, the value of $\Delta E$ of the reaction is, -369.2 KJ