Answer to Question #100046 in General Chemistry for Beverlie

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:
NH4NO2(aq) = N2(g) + 2H2O(l)
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 1.40 L of 0.900 M NH4NO2 decomposes at 25.0°C? answer in atm.

Answer 1

nRT=PV (Mendeleev-Klapeurones law )

n - number of moles, C - concentration M (moles/Litres), V - Volume gas(L), R - constant , P - pressure, T- absolutle Temperature (*K)

n=C * V

n=1.26 moles of NH4NO2

reaction, consider the decomposition of ammonium nitrite:

NH₄NO₂(aq) = N₂(g) + 2H₂O(l) 

n_NH4NO2=n_N2

Product of gas-fase only N2

At 25*C=298*K,

P=nRT/V

P=1.26*298*R/10.0, R=0.082 atm*Litres/moles*K

P=3.079 atm