The standard heat of the reaction 4NH_3(g) + 5O_2(g) rightarrow 4NO_(g) + 6H_2O_

Question

The standard heat of the reaction 4NH_3(g) + 5O_2(g) rightarrow 4NO_(g) + 6H_2O_(g) is Delta H_r degree = -904.7 kJ a) Briefly explain what that means. Your explanation may take the form when ___ (specify quantities of reactant species and their physical state), the change in enthalpy is ___: b) Is the reaction exothermic or endothermic at 25 degree C? would you have to heat or cool the reactor to keep the temperature constant? What would the temperature do it the reactor can adiabatically? what can you infer about the energy required to break the molecular bonds of the reactants and that released when the product bonds form? c) What is Delta H_r degree for 2NH_3(g) + 5/2OO_2 rightarrow 2NO(g) + 3H_2O(g) d) What is Delta H_r degree for NO_(g) + 3/2 H_2O_(g) rightarrow NH_3 (g) + 5/4 O_2 e) Estimate the enthalpy change associated with the consumption of 340g NH_3/s if the reactants products are all at 25 degree C. What have you assumed about the reactor pressure? f) The values of Delta H_r degree given in this problem apply to water vapor at 25 degree C and 1 atm, yet the norma) building point of water is 100 degree C. Can water exist as a vapor at 25 degree C a total pressure of 1 atm?

Explanation / Answer

4NH3(g)+5O2(g)-------4NO(g)+ 6H2O(g) , deltaH=-904.7 Kj

1.When 4 moles of NH3 reacts with 5 moles of oxygen 4 moles of NO and 6 moles of H2O(g are generated along with 904.7 KJ

2. Since heat is liberated, the reaction is exothermic, the reactor will have to be cooled to keep the reactor under isothermal conditions. If the reactor is operated adiabatically, the heat liberated heats the reaction mixture and as a results the temperature increased. The heat generated is

=Energy required to break the reactant molecules - Energy required to form break the product molecules.

3. for the reaction, 2NH3(g)+(5/2)O2(g)-------2NO(g)+ 3H2O(g), the enthalpy change at standard conditions is -904.7/2= -452.35 Kj

4. for the reaction   2NO(g)+3H2O(g) -------à2NH3(g)+ (5/2)O2(g), deltaH= 452.35 Kj

For the reaction NO(g)+(3/2) H2O(g) ----à NH3(g)+ (5/4)O2(g), deltaH= 452.35/2= 226.175 Kj

5. moles of NH3= mass/molar mass= 340/17= 20 moles.

4 moles of NH3 gives 904.7 Kj of heat

20 moles of NH3 gives 904.7*20/4 Kj=4523.5 Kj. The reactor pressure at standard conditions is assumed to be 1 bar.

6. Assuming the gases after liberation of heat are brought to standard conditions of 1 atm and 25 deg.c, the heat liberated is defined as standard heat of reaction.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.