Question

In some aquatic ecosystems, nitrate (NO3–) is converted to nitrite (NO2–), which then decomposes to nitrogen and water. As an example of this second reaction, consider the decomposition of ammonium nitrite: What would be the change in pressure in a sealed 10.0 L vessel due to the formation of N2 gas when the ammonium nitrite in 2.20 L of 1.10 M NH4NO2 decomposes at 25.0°C?

Answer 1

The equation is:

NH₄NO₂ (aq) → N₂ (g) + 2H₂O (l)

The moles of NH₄NO₂ (aq) is:

M ₓ V = 1.10 ₓ 2.20 = 2.4 moles of NH₄NO₂

1 mole of NH₄NO₂ = 1 mole of N₂

2.4 mole = 2.4 mole of N₂

No liquid volume = V total - V liquid = 10 - 2.20 = 7.8 liters.

Now, substituting the data in the equation PV = nRT we get:

PV = nRT

P = nRT/V

P = 2.4 ₓ 0.082 ₓ 298 / 7.8

P = 7.5 atm