Question

g The following reaction is the first step in the production of nitric acid from ammonia. 4NH3(g) 5O2(g) → 4NO(g) 6H2O(g) Calculate the standard enthalpy change, in kJ, for this reaction

Answer 1

Answer: The enthalpy of the reaction is coming out to be -902 kJ.

Explanation:

Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. It is represented as $\Delta H$

The equation used to calculate enthalpy change is of a reaction is:  

$\Delta H_{rxn}=\sum [n\times \Delta H_f_{(product)}]-\sum [n\times \Delta H_f_{(reactant)}]$

For the given chemical reaction:

$4NH_3(g)+5O_2(g)\rightarrow 4NO(g)+6H_2O(g)$

The equation for the enthalpy change of the above reaction is:

$\Delta H_{rxn}=[(4\times \Delta H_f_{(NO(g))})+(6\times \Delta H_f_{(H_2O(g))})]-[(4\times \Delta H_f_{(NH_3(g))})+(5\times \Delta H_f_{(O_2)})]$

We are given:

$\Delta H_f_{(NO(g))}=91.3kJ/mol\\\Delta H_f_{(H_2O(g))}=-241.8kJ/mol\\\Delta H_f_{(NH_3(g))}=-45.9kJ/mol\\\Delta H_f_{(O_2)}=0kJ/mol$

Putting values in above equation, we get:

$\Delta H_{rxn}=[(4\times (91.3))+(6\times (-241.8))]-[(4\times (-45.9))+(5\times (0))]\\\\\Delta H_{rxn}=-902kJ$

Hence, the enthalpy of the reaction is coming out to be -902 kJ.

Answer 2

The enthalpy of reaction for the first step of the production of nitric acid from ammonia is -902 kJ/mol.

Standard enthalpy change

The standard enthalpy change of a reaction cal be calculated using the enthapies of formation of the reactants and the products in the reaction. Recall that the enthalpy of formation of a pure compound is 0 Kj/mol.

Enthalpy of formation of ammonia = -45.9 kJ/mol

Enthalpy of formation of nitogen monoxide = 91.3 kJ/mol

Enthalpy of formation of gaseous water = -241.8 kJ/mol

Enthalpy of formation of oxygen = 0 kJ/mol

ΔHrxn = [4(91.3 kJ/mol) + 6( -241.8 kJ/mol)] - [4(-45.9 kJ/mol) + 5( 0 kJ/mol)]

ΔHrxn = [365.2 - 1450.8] + 183.6 = -902 kJ/mol

Learn more about enthalpy of reaction: https://brainly.com/question/4144781