LHA old EXAM Solns

 

  1. B
  2. A
  3. A (1 moles/L; others are 0.5 moles/L)
  4. D
  5. E  none of the above(answer 317.5kPa)
  6. A
  7. D
  8. A
  9. A
  10. B
  11. C
  12. D
  13. C
  14. A
  15. C
  16. A
  17. C
  18. B
  19. A
  20. C
  21. 6.36 L (first apply ratio; then use PV = nRT)
  22. 44 800 mL
  23. Q = 8749 J; n = 0.0617 moles; DH/n = -142 kJ/mole
  24. O2
  25. 0.659 L
  26. –300(4.19)(x-20)=100(0.032)(x – 90)

   x = 20.2 C

  1. 6 new circles are exposed; old area was 8pr2; now 14 pr2; so it will react 14/8 times faster.
  2. DH=104 +3(-394)+4(-242) = -2046 kJ/mole of propane
  3. DH= 2(-242) + -394 + 75 = -803 kJ
  4. solid only has vibrational motion; gas has vibrational, rotational and translational motions
  5. a.         lowest mountain actually has the highest avg. speed

 

b. draw a vertical line on the right hand edge of the first curve

 

  1. Add sand to remove oxygen supply. Adding water would only add fuel to this particular fire. Heat is difficult to control in this case; Na even reacts with ice.
  2. 2-0.5 = 1.5 moles of nitrogen reacted. From ratio twice as much ammonia forms = 3.0 moles. So rate = 3.0 moles/300 s = 0.010 moles/s
  3. After 5 seconds, original 4 – 3 left = 1.0 mole of BC reacted. After 25 s, 2.8 moles reacted. So that’s an avg of  (2.8 – 1.0)/(25-5) = 0.090 moles BC/s. See ratio:

0.090/2 moles of B = 0.045 moles/s are produced on avg.

35. a,a,a,b