Question

AsNH₃(g) is decomposed into nitrogen gas and hydrogen gas at constant pressure and temperature, the volume of the product gases collected is twice the volume of AsNH₃ (g) reacted. Explain. AsNH₃ (g) is decomposed into nitrogen gas and hydrogen gas at constant volume and temperature, the total pressure increases by some factor. Why does the increase in pressure occur, and by what factor does the total pressure increase when reactants are completely converted into products? How do the partial pressures of the product gases compare to each other and to the initial pressure of NH₃ (g)?

Answer 1

The volume of the product gases is twice the volume of AsNH₃(g) reacted due to Avogadro's Law. An increase in total pressure under constant volume is because of an increase in the total number of gas molecules. The partial pressures of the product gases would be proportional to their mole fractions according to Dalton’s law.

Step-by-step explanation:

The increase in the volume of gaseous products as compared to the volume of AsNH₃(g) reacted is a reflection of the balanced equation of the decomposition reaction, which expresses stoichiometric ratios. According to Avogadro's law, equal volumes of gases at the same temperature and pressure contain an equal number of molecules. Therefore, the larger volume of product gases indicates a larger number of molecules of product gases, which is consistent with the balanced equation.

When the reaction is run at constant volume, the increase in total pressure is due to the increase in the number of molecules of gases present. If we assume complete conversion of AsNH₃(g) into nitrogen and hydrogen gases, the total pressure would increase in proportion to the total number of moles of product gases as compared to the initial moles of AsNH₃(g).

The partial pressures of the product gases would be directly proportional to their respective mole fractions in the gas mixture, according to Dalton's law of partial pressures. If the balanced equation shows an equal number of moles of nitrogen and hydrogen gases are produced, the partial pressures of these gases would be equal to each other and each would be half of the total pressure.

Learn more about Gas Laws