Question

The feed to an ammonia synthesis reactor contains 25 mole% nitrogen and the balance hydrogen. The fow rate of the stream is 3000 kg/h. Calculate the rate of flow of nitrogen into the reactor in kg/h. (Suggestion: First calculate the average molecular weight of the mixture.)

Answer 1

Answer:

The rate of flow of nitrogen into the reactor is 2,470.588 kg/h.

Explanation:

Mole percentage of nitrogen gas  = 25 mole%

Mole percentage of hydrogen  gas  = 75 mole%

Average molecular weight of the mixture:

$(0.25\times 28 g/mol)+(0.75\times 2 g/mol)=8.5 g/mol$

Rate of flow of the stream = 3000 kg/h

Mass of stream in 1 hour = 3000 kg = 3,000,000 g

Moles of stream :

$\frac{3000 g}{8.5 g/mol}=352,941.17 mol$

Moles of nitrogen gas in 352,941.17 moles of stream be x

$25\%=\frac{\text{Moles of nitrogen gas}}{\text{Moles of stream}}\times 100$

$25=\frac{x}{352,941.17mol}\times 100$

x = 88,235.294 mol

Mass of 8,823,529.4 mole of nitrogen gas:

$88235.294 mol\times 28 g/mol=2.470588.2 g=2,470.588 kg$

The rate of flow of nitrogen into the reactor is 2,470.588 kg/h.