6) 2 kg of Oxygen is heated from 30C to 130C. Determine the amount of heat needed if this is done at (a) constant volume and (b) constant pressure. Solve this problem using thermodynamic tables, as well as by using average specific heat, and compare your answers. TABLE A-2 Ideal-gas specific heats of various common gases (a) At 300 K Gas Air Argon Butane Carbon dioxide Carbon monoxide Ethane Ethylene Helium Hydrogen Methane Neon Nitrogen Octane Oxygen Propane Steam Formula Ar CH0 CO CH6 CH He H CH Ne N CgH18 02 C3H8 HO Gas constant, R kJ/kg-K 0.2870 0.2081 0.1433 0.1889 0.2968 0.2765 0.2964 2.0769 4.1240 0.5182 0.4119 0.2968 0.0729 0.2598 0.1885 0.4615 Cp kJ/kg-K 1.005 0.5203 1.7164 0.846 1.040 1.7662 1.5482 5.1926 14.307 2.2537 1.0299 1.039 1.7113 0.918 1.6794 1.8723 APPENDIX 1 kJ/kg-K 0.718 0.3122 1.5734 0.657 0.744 1.4897 1.2518 3.1156 10.183 1.7354 0.6179 0.743 1.6385 0.658 1.4909 1.4108 Note: The unit kJ/kg-K is equivalent to kJ/kg-C. Source of Data: B. G. Kyle, Chemical and Process Thermodynamics, 3rd ed. (Upper Saddle River, NJ: Prentice Hall, 2000). k 1.400 1.667 1.091 1.289 1.400 1.186 1.237 1.667 1.405 1.299 1.667 1.400 1.044 1.395 1.126 1.327 TABLE A-1 Molar mass, gas constant, and critical-point properties Substance Air Ammonia Argon Benzene Bromine n-Butane Carbon dioxide Carbon monoxide Carbon tetrachloride Chlorine Chloroform Dichlorodifluoromethane (R-12) Dichlorofluoromethane (R-21) Ethane Ethyl alcohol Ethylene Helium n-Hexane Hydrogen (normal) Krypton Methane Methyl alcohol Methyl chloride Neon Nitrogen Nitrous oxide Oxygen Propane Propylene Sulfur dioxide Tetrafluoroethane (R-134a) Trichlorofluoromethane (R-11) Water Xenon Formula NH3 Ar CH6 Br CH10 CO CO CCIA Cl CHCI 3 CCIF CHCIF CH6 CH5OH CH He C6H1 H Kr CH CHOH CH3CI Ne N N0 0 C3H8 C3H6 SO CF3CHF CCI3F HO Xe Molar mass, M kg/kmol 28.97 17.03 39.948 78.115 159.808 58.124 44.01 28.011 153.82 70.906 119.38 120.91 102.92 30.070 46.07 28.054 4.003 86.179 2.016 83.80 16.043 32.042 50.488 20.183 28.013 44.013 31.999 44.097 42.081 64.063 102.03 137.37 18.015 131.30 Gas constant, R kJ/kg-K* 0.2870 0.4882 0.2081 0.1064 0.0520 0.1430 0.1889 0.2968 0.05405 0.1173 0.06964 0.06876 0.08078 0.2765 0.1805 0.2964 2.0769 0.09647 4.1240 0.09921 0.5182 0.2595 0.1647 0.4119 0.2968 0.1889 0.2598 0.1885 0.1976 0.1298 0.08149 0.06052 0.4615 0.06332 Critical-point properties Temperature, Pressure, MPa K 132.5 405.5 151 562 584 425.2 304.2 133 556.4 417 536.6 384.7 451.7 305.5 516 282.4 5.3 507.9 33.3 209.4 191.1 513.2 416.3 44.5 126.2 309.7 154.8 370 365 430.7 374.2 471.2 647.1 289.8 3.77 11.28 4.86 4.92 10.34 3.80 7.39 3.50 4.56 7.71 5.47 4.01 5.17 4.48 6.38 5.12 0.23 3.03 1.30 5.50 4.64 7.95 6.68 2.73 3.39 7.27 5.08 4.26 4.62 7.88 4.059 4.38 22.06 5.88 Volume, m/kmol 0.0883 0.0724 0.0749 0.2603 0.1355 0.2547 0.0943 0.0930 0.2759 0.1242 0.2403 0.2179 0.1973 0.1480 0.1673 0.1242 0.0578 0.3677 0.0649 0.0924 0.0993 0.1180 0.1430 0.0417 0.0899 0.0961 0.0780 0.1998 0.1810 0.1217 0.1993 0.2478 0.0560 0.1186