1. A pure substance has a specific volume of 0.08 L/mol at a pressure of 3 atm and 298 K. The substance is most likely:

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1 Name: September 19, 2014 EXAM 1 P a g e 1 1. A pure substance has a specific volume of 0.08 L/mol at a pressure of 3 atm and 298 K. The substance is most likely: a. Liquid b. Gas c. Supercritical Fluid d. Vapor 2. A rigid tank contains CO2 at 2 atm and 50 C. When the tank is heated to 250 C, the pressure increases significantly and the gas density a. Increases b. Decreases c. Remains the Same d. Tank Explodes 3. Two pathways are shown from points 1 to 2 on the pressure-temperature diagram. One pathway has a phase change (dashed line) and the other does not (solid lines). Which pathway has the larger change in enthalpy? a. Solid b. Dashed c. Same for Both d. No Way to Know

2 Name: September 19, 2014 EXAM 1 P a g e 2 4. Which line corresponds to an isotherm for a gas? 5. A fluid flows steadily through a circular pipe of uniform cross-sectional area as shown below. If the outlet density of the fluid decreases to 1/2 of its inlet value, what happens to the average fluid velocity? a. The velocity will not change since mass must be conserved and the flow is steady-state. b. The outlet velocity will be 1/4th of the inlet velocity since kinetic energy must be conserved according to the Bernoulli equation. c. The outlet velocity will be twice the inlet velocity since mass must be conserved in the system. d. The velocity will increase somewhat but we can t tell how much with the information given. e. The velocity will decrease somewhat because of friction between fluid and the pipe wall.

3 Name: September 19, 2014 EXAM 1 P a g e 3 6. A wastewater treatment process requires 100 cubic feet per minute (CFM) of air at STP in order to meet the oxygen demand of the microorganisms. The actual volumetric flowrate of air needed to meet this demand on a winter day (0 oc) in Denver, CO (Patm = 0.83 atm) would be. a. less than 100 CFM b. exactly 100 CFM c. greater 100 CFM d. can't say without more information 7. Consider two vapor mixtures of saturated water in air. One is at 20 o C and 1 atm and the other is at 20 o C and 2 atm. Which one has a higher partial pressure of water? a. The mixture at 20 o C and 1 atm b. The mixture at 20 o C and 2 atm c. The same in both mixtures d. You cannot tell 8. A chemist filled a 1 L flask with ethanol (specific gravity = 0.79) in 20 seconds through a funnel. The time to fill the same flask with water if the mass flow rate is the same would be. a. Shorter b. Longer c. Same d. Can t Tell

4 Name: September 19, 2014 EXAM 1 P a g e 4 9. Propane (C3H8) reacts with oxygen to form carbon dioxide and water C3H8 + 5O2 --> 4H2O + 3CO2 If 50 moles C3H8 enters a reactor with 50 moles O2, and assuming full conversion of the limiting reactant, how many moles of H2O form? a. 200 mols b. 40 mols c. 50 mols d. 30 mols 10. Ammonia is compressed isothermally at 300 K until liquid NH3 forms at pressure Pa. In a second container, ammonia is compressed at 350 K until it condenses at a pressure Pb. The pressure Pa is Pb. a. greater than b. less than c. equal to d. no way to know 11. A sealed container contains water and air. At 100 C, the system is saturated with water, which makes up 25% of the vapor. What is the pressure of the system? a. 1 bar b bar c. 4 bar d. 10 bar

5 Name: September 19, 2014 EXAM 1 P a g e A fixed-volume container at 45 C contains 1 L of liquid benzene and 1 L of benzene vapor in equilibrium. If 0.4 L liquid benzene is removed at constant temperature, the benzene partial pressure. a. increases b. decreases c. remains the same d. not enough information 13. We want to separate a 50/50 mixture of C6 isomers in the gas phase. As the temperature is lowered, a technician states that he observed that some n- hexane (n-c6) condenses before any 2,2- dimethylbutane (DMB) condenses. Does this actually happen? a. Yes, if n-c6 has a lower vapor pressure than DMB. b. Yes, if n-c6 has a higher vapor pressure than DMB. c. No, because both species have to condense. d. It depends on the system pressure as to whether one or two species condense.

6 Name: September 19, 2014 EXAM 1 P a g e A cooling crystallizer operates at 30 C to form salt crystals from a solution of dissolved salt in water. 100 g of solution enters the crystallizer at 100 C. The crystallizer extracts 25 g of salt. What is the mass fraction of salt in the exit stream? a b c d lbm of H2SO4 at 60 F is added to enough water at 60 F to make a 25 wt% solution in an adiabatic vessel. What is the final temperature of the mixture? a. 60 F b. 100 F c. 160 F d. > 200 F

7 Name: September 19, 2014 EXAM 1 P a g e A small tank contains dry air at 25 C. A small beaker of water at 25 C is placed in the container, which is then sealed. The tank is well insulated. When equilibrium is reached, the air temperature is. a. slightly higher b. slightly lower c. the same d. can t tell