How much heat is absorbed/released when 40.00 g of NH₃(g) reacts in the presence of excess $\mathrm { O } _ { 2 }$ (g) to produce NO(g) and H₂O(l) according to the following chemical equation?
4NH₃(g) + 5O₂(g) ? 4NO(g) + 6H₂O(l) $\Delta _ { \mathrm { r } }$ H° = 1168 kJ

Question

How much heat is absorbed/released when 40.00 g of NH₃(g) reacts in the presence of excess

\mathrm { O } _ { 2 }

(g) to produce NO(g) and H₂O(l) according to the following chemical equation?
4NH₃(g) + 5O₂(g) ? 4NO(g) + 6H₂O(l)

\Delta _ { \mathrm { r } }

H° = 1168 kJ

Quizplus · Accepted Answer

The given chemical equation shows that the reaction of 4 moles of NH₃(g) with 5 moles of O2(g) releases 1168 kJ of heat. To calculate the heat released for the given amount (40.00 g) of NH₃(g), we need to first calculate the number of moles of NH₃(g) using its molar mass: Molar mass of NH₃(g) = 14.007 + 1.008 + 32.06 = 47.07 g/mol Number of moles of NH₃(g) = 40.00 g / 47.07 g/mol = 0.8495 mol From the balanced chemical equation, we see that 4 moles of NH₃(g) release 1168 kJ of heat. So, for 0.8495 mol of NH₃(g), the heat released can be calculated as: Heat released = (1168 kJ / 4 mol) x 0.8495 mol = 311.13 kJ However, the question is asking for the heat absorbed/released, which means we need to look at the sign of the given enthalpy change. The enthalpy change ($\Delta _ { \mathrm { r } }$ H°) is positive, which means heat is absorbed during the reaction. Therefore, the correct answer is A) 685.8 kJ of heat are absorbed.

How Much Heat Is Absorbed/released When 40 O2\mathrm { O } _ { 2 }O2​

How Much Heat Is Absorbed/released When 40 $\mathrm { O } _ { 2 }$