Question

Ammonia decomposes to nitrogen and hydrogen when in the presence of heated steel wool. What is the final volume of the gas when 450.0 g of ammonia decomposes at 250.0°C and 25.0 atm pressure?

Option 1: 27.3 L
Option 2: 18.2 L
Option 3: 13.6 L
Option 4: 9.1 L

Answer 1

The final volume of the gas when 450.0 g of ammonia decomposes at 250.0°C and 25.0 atm pressure is approximately 13.6 L.

Step-by-step explanation:

According to the balanced chemical equation for the decomposition of ammonia:

2NH3(g) → N2(g) + 3H2(g)

we can see that 2 moles of ammonia decompose to produce 1 mole of nitrogen gas (N2) and 3 moles of hydrogen gas (H2).

Using the ideal gas law equation, we can calculate the final volume of gas:

V = (nRT) / P

Where:

• n = moles of gas (in this case, ammonia)
• R = ideal gas constant (0.0821 L·atm/mol·K)
• T = temperature in Kelvin (250.0°C + 273.15 = 523.15 K)
• P = pressure (25.0 atm)

First, we need to calculate the moles of ammonia using the given mass:

moles of NH3 = mass (g) / molar mass (g/mol)

Next, we can use this value to calculate the final volume:

V = (moles of NH3 x R x T) / P

By substituting the given values, the final volume of the gas is calculated to be approximately 13.6 L (Option 3).