Question

A Carbon dioxide fire extinguisher initially contains 5.5lbm of CO₂ gas. In “real life” the CO₂ would not be all gas, but for this problem assume that it is. The CO₂ gas has an initial pressure of 860psia and initial temperature of +72^oF. Immediately after putting out a fire, it has a final pressure of 100psia and a final temperature of -30^oF. Assume ideal gas law behavior.

a) Show that the specific gas constant for CO₂ gas is approximately R=1131ft∙lbf/(slug∙R).

b) What is the initial density of the CO₂ gas in the fire extinguisher?

c) What is the initial mass of CO₂ gas in slug?

d) What is the initial internal volume of the fire extinguisher?

e) Assume that the internal volume does not change. What is the final mass-density of CO₂ gas inside the fire extinguisher (at 100psia, -30^oF)?

f) What is the final mass of CO2 gas inside the fire extinguisher? Give answer in both slug and in lbm.

Answer 1