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Problems 661 Section 21.1 Molecular Model of an Ideal Gas 1. In a 30.0-s interval, 500 hailstones strike a glass window of area 0.600 m 2 at an angle of 45.0° to the window surface. Each hailstone has a mass of 5.00 g and moves with a 2. In a period of 1.00 s, 5.00 % 10 23 nitrogen molecules strike a wall with an area of 8.00 cm 2 . If the molecules move with a speed of 300 m/s and strike the wall head-on in elastic 2 molecule is 4.68 % 10 ! 26 kg.) 3. A sealed cubical container 20.0 cm on a side contains 4. A 2.00-mol sample of oxygen gas is confined to a 5.00-L vessel at a pressure of 8.00 atm. Find the average transla- 3 contains helium at an (inside) pressure of 1.20 % 10 5 Pa. How many moles of helium are in the balloon if the average kinetic energy ! 22 J? 6. Use the definition of Avogadro’s number to find the mass of a helium atom. 8. Given that the rms speed of a helium atom at a certain temperature is 1 350 m/s, find by proportion the rms 2 ) molecule at this temperature. The molar mass of O 2 is 32.0 g/mol, and the molar mass of He is 4.00 g/mol. A cylinder contains a mixture of helium and argon gas in equilibrium at 150°C. (a) What is the average 10. A 5.00-L vessel contains nitrogen gas at 27.0°C and a pres- sure of 3.00 atm. Find (a) the total translational kinetic en- 11. (a) Show that 1 Pa # 1 J/m 3 . (b) Show that the density in space of the translational kinetic energy of an ideal gas is Section 21.2 Molar Specific Heat of an Ideal Gas Note: You may use data in Table 21.2 about particular V # 3R/2 and C P # 5R/2, and a “diatomic ideal gas” to have C V # 5R/2 and C P # 7R/2. 9. 7. 5. 12. Calculate the change in internal energy of 3.00 mol of helium gas when its temperature is increased by 2.00 K. A 1.00-mol sample of hydrogen gas is heated at con- stant pressure from 300 K to 420 K. Calculate (a) the 14. A 1.00-mol sample of air (a diatomic ideal gas) at 300 K, 15. In a constant-volume process, 209 J of energy is transferred by heat to 1.00 mol of an ideal monatomic gas initially at 16. A house has well-insulated walls. It contains a volume of 100 m 3 of air at 300 K. (a) Calculate the energy required to increase the temperature of this diatomic ideal gas by 17. An incandescent lightbulb contains a volume V of argon at i . The bulb is switched on and constant power " is transferred to the argon for a time interval "t. f in the bulb at the end of this process is P f # P i [1 $ (""tR)/(P i VC V )]. (b) Find the pres- sure in a spherical light bulb 10.0 cm in diameter 4.00 s af- 18. A vertical cylinder with a heavy piston contains air at a temperature of 300 K. The initial pressure is 200 kPa, and 3 . Take the molar mass of air as 28.9 g/mol and assume that C V # 5R/2. (a) Find the specific heat of air at constant volume in units of J/kg & )C. 19. A 1-L Thermos bottle is full of tea at 90°C. You pour out 20. A 1.00-mol sample of a diatomic ideal gas has pressure P and volume V. When the gas is heated, its pressure triples 13. 1, 2 , 3 = straightforward, intermediate, challenging = full solution available in the Student Solutions Manual and Study Guide = coached solution with hints available at http://www.pse6.com = computer useful in solving problem = paired numerical and symbolic problems P R O B L E M S |