Page 258 - Schaum's Outline of Theory and Problems of Applied Physics

CHAP. 20] KINETIC THEORY OF MATTER 243

20.12. How many moles are present in 120 kg of boric acid (H 3 BO 3 )? The atomic mass of boron is 10.82 u.

20.13. (a) Find the mass of 80 mol of sulfuric acid (H 2 SO 4 ). (b) How many oxygen atoms are present?
20.14. (a) What volume does 8.2 mol of fluorine (F 2 ) occupy at STP? (b) What volume does it occupy at 40 C and a
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pressure of 2.5 atm?

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20.15. (a) What volume does 5 g of methane (CH 4 ) occupy at STP? (b) What volume does it occupy at 0 C and a pressure
of 0.5 atm? (c) What volume does it occupy at 80 C and a pressure of 2 atm?
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20.16. (a) What volume does 20 g of CO 2 occupy at STP? (b) What volume does it occupy at −20 C and a pressure of 4
atm?
20.17. What is the mass of4Lof ammonia (NH 3 ) at STP?
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20.18. (a) Find the mass of 12 L of chlorine (Cl 2 )at40 C and 0.8 atm of pressure. (b) What is its density under those
conditions?
4
3
20.19. A balloon is filled with 50 m (5 ×10 L) of hydrogen at STP. What is the mass of the hydrogen?
20.20. Find the density of sulfur dioxide (SO 2 ) at STP.

20.21. Find the density of nitrogen (N 2 )at120 C and a pressure of 66,600 Pa.
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20.22. One liter of an unknown gas has a mass of 2.9 g at STP. Find its molecular mass.

Answers to Multiple-Choice Questions

20.1. (a) 20.8. (a), (c)

20.2. (b) 20.9. (c)

20.3. (d) 20.10. (a)

20.4. (a) 20.11. (b)
20.5. (c) 20.12. (b)

20.6. (b) 20.13. (b)

20.7. (d)

Answers to Supplementary Problems

20.1. The pressure decreases partly because the gas molecules now must travel farther between impacts on the container
walls and partly because these impacts are now distributed over a larger area.

20.2. The pressure increases partly because the gas molecules move faster than before and therefore strike the walls more
often and partly because each impact yields a greater force than before.

20.3. Lower