Question

Ammonia is a gas for which reliable analytical methods are available to determine its concentration in other gases. To measure flow in a natural-gas pipeline, pure ammonia gas is injected into the pipeline at a constant rate of 72.3 kg/min for 12 min. Five miles downstream from the injection point, the steady-state ammonia concentration is found to be 0.382 wt %. The gas upstream from the point of ammonia injection contains no measurable ammonia. How many kilograms of natural gas are flowing through the pipeline per hour?

Answer 1

amount of ammonia injected:

72.3 kg/min x 12 min = 867.6 kg

ammonia concentration = 0.382%

$\tt 0.382\%=\dfrac{mass~amonia}{mass~ammonia+mass~natural~gas}\times 100\%\\\\0.00382=\dfrac{867.6}{867.6+mass~natural~gas}\\\\mass~natural~gas=226,252.88~kg/12min=1131264.4~kg/h$