cee111-fa07-mt1-Nazaroff-exam

# cee111-fa07-mt1-Nazaroff-exam - 1 CE 111 Environmental...

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Unformatted text preview: 1. CE 111: Environmental Engineering MTDTERi'v-I EXAM it it} lDctoher 211i]? 1. Water in air {4 points; 1 each] The data below describe a parcel of air. Answer the following questions using these data. {a} What 1s the molar concentration of water vapor?I (units: moli'sm J (b) What 15 the mole fraction of 1Water vapor in the air? (units: —]I {c} What is the partial pressure of water vapor? (units: atm or Pa} (d) What is the relative humidity? (units: w— or %) Doro: Cum: 4 g 111'“ mass concentration of water vapor in air T = 298 K _ air temperature P = 1 atm = l.ﬂ1325 x 1D” Pa air pressure Pm = 3 15:1 Pa (saturation) vapor pressure of water at 298 K 2. Balancing a redox reaction [4 points} Hypoehlorous acid {HOCI} is used to disinfect drinking water. When HDCl is applied to water as a disinfectant some of it is consumed rapidly because it oxidizes chemical impurities in the water. Write a balanced redox reaction for die oxidation of aqueous hydrogen sulfide (HES) to Sulfate (SO42 } by chlorine in hypoehlorous acid (HDCI) being converted to chloride {Cl' }. 3. Kinetics in a batch reactor {4 points; 2 each}, Consider a batch reactor in which the following reaction occurs: A+B—1products a=a[a1 11=1115 a" At time t= ii, the concentrations in the reactor are [AHUJ = 5 111le and [E]{D) = II] ml'v‘l. {a} What is [A] at t= 3 days? (b) What is [B] at t= .1 days? 4. Naphthalene: No NAF'L {4 points] A sealed container contains liquid water and air. A quantityr of M moles of naphthalene (Clam, MW = 128 gimol) is injected into container. Consider the equilibrium partitioning of naphthalene among its possible phases. If M is small, then the naphthalene will partition into two states: gas phase and aqueous phase. it'M is large, then the naphthalene will be in three states: gas phase, aqueous phase, plus a nonaqueous phase liquid (NAPL). Given the data below, determine the maximum value of M that can he added to the container such that there is no NAPL of naphthalene in The system. Doro: Kn = 2.3 M atm'I Henry’s lav.r constant for naphthalene Pm = 111.15 Pa {saturation} vapor pressure of naphthalene Cm = 3-1 rngi'L water solubility of naphthalene T = 293 K temperature Va: 3i] L = D.il3 r115 volume of air in the container V“ == 2 L volume of liquid water in the container 5. Settling flux {4 points} A cubical chamber is ﬁlled with l m of water. To this is added it] g of partlculate matter. The particles are spherical and all have the same diameter and density so that they settle at a uniform velocity, v,= 5 m h At time r— — i], the particle concentration is uniform throughout the chamber and the water is motionless. Consider a position that is slightly above the bottom of the chamber. Sketch a plot that shows the particle ﬂux [y-axis) at this position as a function of time {it-axis}. Be sure to label your coordinate axes and to indicate the proper numerical values off the flux and time scale. ...
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