FA2019 Exam 2 Sample.pdf - SAMPLE TEST#2 CHBE 221 1(30 pts Experiments are performed on a certain gas and it is determined that it has a vapor pressure

FA2019 Exam 2 Sample.pdf - SAMPLE TEST#2 CHBE 221 1(30 pts...

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CHBE 221 SAMPLE TEST #2 1 (30 pts) Experiments are performed on a certain gas, and it is determined that it has a vapor pressure of 573 mm Hg at 60 ℃ and a vapor pressure of 796 mm Hg at 70 ℃ . Estimate the vapor pressure at 90 ℃ using the data above. Do NOT try a linear extrapolation! The best method using this data will give an error of about 1% for the vapor pressure. 2 (35 pts) A certain gas (MW 29) has known critical temperature and critical pressure. In the absence of charts or tables, an engineer is curious how well the classic van der Waals equation 𝑃 ൌ 𝑅𝑇 𝑉 െ 𝑏 𝑎 𝑉 would work for predicting PVT in the supercritical fluid regime. He charges a cylinder of volume 250 L with 21 kg of the gas. He finds it has an absolute pressure of 50 atm at a temperature of ሺെ50 ℃ሻ . Use the van der Waals equation to predict the compressibility factor
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Unformatted text preview: for the gas and compare this value to the actual value from the measured conditions. The known ௖ , ௖ give van der Waals parameters ൌ 1.33 atm ൬ L mol ൰ ଶ ൌ .0366 ൬ L mol ൰ Gas Constant: ൌ .08206 ୟ୲୫ ୐ ୫୭୪ ୏ 3 (35 pts) A bubble column operating at steady state at a pressure of 3 atm and a temperature of 100 ℃ contains liquid at a mole fraction of 60% n-hexane ( ଺ ଵସ ሻ and 40% n-heptane ሺ ଻ ଵ଺ ሻ . Pure nitrogen gas at the stated conditions is bubbled through the column with a feed rate of 20.4 L/s . Find the composition and mass flow rate of the exiting gas stream . Vapor pressures at 100 ℃: n-hexane: ∗ ൌ 1846 mm Hg n-heptane: ∗ ൌ 796 mm Hg Molecular weight: ଶ ൌ 28; ଺ ଵସ ൌ 86; ଻ ଵ଺ ൌ 100 1 atm = 760 mm Hg...
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