Blue Book Flash Card

41. An ideal gas at 0.80 atmospheres and 87°C occupies 0.450 liter. How many moles are in the

sample? (R = 0.0821 liter-atm/mole-K).

A. 0.0002 mole

B. 0.0378 mole

C. 0.0122 mole

D. 0.0091 mole

42. A certain gas at 101.325 kPa and 10°C whose volume is 2.83 m3

capacity. Before admission,

the storage vessel contained gas at a pressure and temperature of 137.8 kPa and 26°C; after

admission, the pressure increased to 1171.8 kPa. What should be the final temperature of the

gas in the vessel in Kelvin?

A. 298.0

B. 319.8

C. 180.0

D. 314.2

43. A perfect gas has a value of R = 58.8 ft-lb/lb-°R and k = 1.26. If 20 Btu are added to 10 lbs of this gas at constant volume when initial temperature is 90°F, find the final temperature.

A. 97°F

B. 104°F

C. 154°F

D. 185°F

44. Ammonia weighing 22 kg is confirmed inside a cylinder equipped with a piston has an initial

pressure of 413 kPa at 38°C. If 3200 kJ of heat is added to the ammonia until its final pressure

and temperature is 413 kPa and 100°C, respectively. What is the amount of work done by the

fluid in kJ?

A. 667

B. 304

C. 420

D. 502

45. A tank contains 90 ft3

of air at a pressure of 350 psig; if the air is cooled until its pressure

and temperature decreases at 200 psig and 70°F respectively, what is the decrease in internal

energy?

A. 6232.09 Btu

B. -5552 Btu

C. 5552 Btu

D. -6232.09 Btu

46. A large mining company was provided with a 3 m3

of compressed air tank. Air pressure in

the tank drops from 700 kPa to 150 kPa while the temperature remains constant at 28°C. What

percentage has the mass of air in the tank been reduced?

A. 74.09

B. 72.45

C. 76.56

D. 78.57

47. A 4 m³ /hr pump delivers water to a pressure tank. At the start, the gage read 138 kPa until it reads 276 kPa and then the pump was shut off. The volume of the tank is 180 liters. At 276

kPa, the water occupied 2/3 of the tank volume. Determine the volume of the water that can

be taken out until the gage reads 138 kPa.

A. 31.20 liters

B. 34.59 liters

C. 16.87 liters

D. 29.50 liters

48. A refrigeration plant is rated at 15 tons capacity. How many pounds of air per hour will it

cool from 70°F to 90°F at constant temperature?

A. 50,000 lb/hr

B. 37,500 lb/hr

C. 52,000 lb/hr

D. 45,000 lb/hr

49. An air standard engine has a compression ratio of 18 and a cut-off ratio of 4. If the intake air

pressure and temperature are 100 kPa and 27°C, find the work in kJ per kg.

A. 2976

B. 2166

C. 1582

D. 2751

50. Determine the air-standard efficiency of an engine operating on the diesel cycle with a

clearance of 6% when the suction pressure is 99.7 kPa and the fuel is injected for 7% of the

stroke. Assume k = 1.4.

A. 62.11%

B. 51.20%

C. 73.58%

D. 60.02%

51. Steam at 2 MPa and 250°C in a rigid cylinder is cooled until the quality is 30%. Find the heat

rejected from the cylinder.

@ 2 Mpa and 250°C: υ = 0.11144 m3

/kg u = 2679.6 kJ/kg

@ 2 Mpa, (saturated):υf = 0.0011767 m3

/kg υg = 0.09963 m3

/kg

uf = 906.44kJ/kg ug = 1693.8 kJ/kg

A. -423.23 kJ/kg

B. -926.26 kJ/kg

C. -1265.02 kJ/kg

D. 1082.34 kJ/kg

52. At 1.3 MPa, a mixture of steam and water has an entropy of 3 kJ/kg-K, Find the enthalpy of

the mixture.

@ 1.3MPa: sf = 2.2515 kJ/kg-K sg = 6.4952 kJ/kg-K

hf = 814.93 kJ/kg hfg = 1972.7 kJ/kg

A. 1627.71 kJ/kg

B. 1533.33 kJ/kg

C. 1234.45 kJ/kg

D. 1162.40 kJ/kg

53. A mixture with 70% quality at 500 kPa is heated isothermally until its pressure is 300 kPa.

Find the heat added during the process.

@ 600 kPa: sf = 1.8607 kJ/kg-K sfg = 4.9606 kJ/kg-K

@ 300 kPa and 151.86°C: s = 7.0888 kJ/kg-K

A. 745.92 kJ/kg

B. 535.16 kJ/kg

C. 982.44 kJ/kg

D. 765.34 kJ/kg

54. A tank contains exactly one kilogram of water consisting of liquid and vapor in equilibrium

at 1 MPa. If the liquid contains one-third and the remaining is vapor of the volume of the tank,

what is the enthalpy of the contents of the tank?

@ 1MPa: υf = 0.0011273 m3

/kg υfg = 0.19444 m3

/kg

hf = 762.81 kJ/kg hfg = 2015.3 kJ/kg

A. 644.40 kJ/kg

B. 774.40 kJ/kg

C. 785.92 kJ/kg

D. 435.29 kJ/kg

55. Water substance at 70 bar and 65°C enters a boiler tube of constant inside diameter of 25

mm. The water leaves the boiler tube at 50 bar and 700 K at velocity of 150 m/s. Calculate the

inlet velocity (m/s).

From steam tables:

@ 70 bar (7Mpa) and 65°C: υ1 = 0.001017 m3

/kg

@ 50 bar (5Mpa) and 700 K (427°C): υ2 = 0.06081 m3

/kg

A. 1.56

B. 2.51

C. 1.672

D. 3.230

56. Water substance at 70 bar and 65°C enters a boiler tube of constant inside diameter of 35

mm. The water leaves the boiler tube at 50 bar and 700 K at velocity of 150 m/s. Calculate the

inlet volume flow (liters/s).

From steam tables:

@ 70 bar (7Mpa) and 65°C: υ1 = 0.001017 m3

/kg

@ 50 bar (5Mpa) and 700 K (427°C): υ2 = 0.06081 m3

/kg

A. 0.821

B. 1.261

C. 0.344

D. 1.609

57. Steam leaves an industrial boiler at 827.4 kPa and 171.6°C. A portion of the steam is passed

through a throttling calorimeter and is exhausted to the atmosphere when the calorimeter

pressure is 101.4 kPa. How much moisture is leaving the boiler container if the temperature of

the steam at the calorimeter is 115.6°C?

@ 827.4 kPa and 171.6°C: hf = 727.25 kJ/kg hfg = 2043.2 kJ/kg

@ 101.4 kPa and 115.6°C: h2 = 2707.6 kJ/kg

A. 3.78%

B. 3.08%

C. 4.56%

D. 2.34%

58. A throttling calorimeter is connected to a desuperheated steam line supplying steam to the

auxiliary feed pump on a ship. The line pressure measures 2.5 MPa. The calorimeter pressure is

110 kPa at 150°C. Determine the entropy of the steam line.

@ 110 kPa and 150°C: h2 = 2775.6 kJ/kg

@ 2.5 MPa: hf = 962.11 kJ/kg hfg = 1841 kJ/kg

sf = 2.5547 kJ/kg-K sfg = 3.7028 kJ/kg-K

A. 6.8 kJ/kg-K

B. 6.2 kJ/kg-K

C. 6.6 kJ/kg-K

D. 7.5 kJ/kg-K

59. Atmospheric pressure boils at 212°F. At the vacuum pressure at 24 in Hg, the temperature is

142°F. Find the boiling temperature when the pressure is increased by 40 psia from

atmospheric.

A. 449.42°F

B. 536.34°F

C. 479.13°F

D. 263.45°F

60. A certain coal has the following ultimate analysis:

C = 69% N2 = 5% H = 2.5% S =7%

Determine the amount of oxygen if the heating value of fuel is 26,961.45 kJ/kg.

A. 1.5%

B. 2.5%

C. 3.5%

D. 4.5%