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McCabe • 2.4 A continuous gravity decanter is to separate chlorobenzene, with a density of 1,109 kg/m3, from aqueous wash liquid having a density of 1,020 kg/m3. Of the total depth in the separator is 1m and the interface is to be 0.6m from the vessel floor, (a) what should the height of the heavy-liquid overflow leg be; and (b) how much would an error of 50mm in this height affect the position of the interface?



• Given: • Density (chlorobenzene) = 1,109 kg/m3 Height (aqueous wash liquid) = ? • Density (aqueous wash liquid) = 1,020 kg/m3 Height (total) = 1m • Height (chlorobenzene) = 0.6m



• 2.8 A U-tube manometer indicates a pressure drop of 10in. water across an air filter. The air is at 26°C and a gauge pressure of 60lbf/in2. (a) what is the pressure drop in lbf/in2 and in atm? (b) What percentage of error is introduced if the density of the air in the manometer lead is neglected?



Given: • Temperature (air) = 26°C • Pressure drop = 10in water • Pressure (gauge) = 60lbf/in2



Practice Problems • 1.8 In your own words, what actions need to be taken in each step of the grid method? Answer: Using the grid method in conversion of units. All units should be properly arrange in order to cancel the units correctly.



• A spherical soap bubble has an inside radius R, a film thickness t, and a surface tension σ. Derive a formula for the pressure within the bubble relative to the outside atmospheric pressure. What is the pressure difference for a bubble with a 4 mm radius? Assume σ is the same as for pure water.



• Solution:



σL = F σ(4x2πR) = P(A) 8πRσ = P(4πR2) P = 4σ/R



• If R=4mm Solution:



P = 4σ/R P = 4(0.073 N/m)/(0.004m) P = 73.0 N/m2