12 For the following cycle which step represents heat reject

12. For the following cycle, which step represents heat rejection a, b d. a 13. 10 grams H20 (gas), 30 grams coz What is average molecular weight? a, 18 (gas). b, 26 c, 32 d.. 37 14. The standard heat of formation at 298K is a measure of a. Energy required to produce molecules from absolute zero b. The sum of the heat of formation of the constituent elements c. The bond energy of any covalent bonds d. The total energy required to form the molecule 15. How many Btu s are needed to isothermally compress 4 lbm of 240 Fair to twice the original pressure? a. 715 b. 428 C. 1800 d. 16. 2 lbm of 200 F iron (cp 0.1) dropped into a gallon of 40 F water. What is final temperature of the mixture? a. 44 F b. 101 F C. 96 F d. 25 F 17. How much energy is required to vaporize 11bm water from 75 Fand 14 psia? a. 110.7 Btu b. 1007 Btu c. 18 Btu d, 45 Btu

Solution

12. d. (d to a) Process.

Given Cyle is the air standard Deisel Cycle.

The above figure shows diesel cycle on both P-V & T-S diagrams.

13.10 c. 32

Given Description Mass(g) Molecular Weight Mole = Mass/Molecular Weight

   H2O gas 10 18.02 10/18.02 =0.554

   CO2 gas 30 44.0 30/44.01=0.682

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   Mixture 40 x 1.2316

   there fore x = Mass/no.of moles = 40/1.2316 = 32.4 ie 32.

14. b. The some of the heat of formation of thr constituent element.

Definition -- The standard enthalpy of formation or standard heat of formation of a compound is the change of enthalpy during the formation of 1 mole of the compound from its constituent elements, with all substances in their standard states at 1 atmosphere (1 atm or 101.3 kPa). Its symbol is Ho
f or _fH^o. The superscript Plimsoll on this symbol indicates that the process has occurred under standard conditions at the specified temperature (usually 25 °C or 298.15 K).

15.