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General Chemistry Principles, Patterns, and Applications, 2011

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14. Determine the density of O 2 under each set of conditions.<br />

a. 42 g at 1.1 atm <strong>and</strong> 25°C<br />

b. 0.87 mol at 820 mmHg <strong>and</strong> 45°C<br />

c. 16.7 g at 2.4 atm <strong>and</strong> 67°C<br />

15. At 140°C, the pressure of a diatomic gas in a 3.0 L flask is 635 kPa. The mass of the gas is 88.7 g. What is the<br />

most likely identity of the gas?<br />

16. What volume must a balloon have to hold 6.20 kg of H 2 for an ascent from sea level to an elevation of 20,320<br />

ft, where the temperature is −37°C <strong>and</strong> the pressure is 369 mmHg?<br />

17. What must be the volume of a balloon that can hold 313.0 g of helium gas <strong>and</strong> ascend from sea level to an<br />

elevation of 1.5 km, where the temperature is 10.0°C <strong>and</strong> the pressure is 635.4 mmHg?<br />

18. A typical automobile tire is inflated to a pressure of 28.0 lb/in. 2 Assume that the tire is inflated when the air<br />

temperature is 20°C; the car is then driven at high speeds, which increases the temperature of the tire to<br />

43°C. What is the pressure in the tire? If the volume of the tire had increased by 8% at the higher<br />

temperature, what would the pressure be?<br />

19. The average respiratory rate for adult humans is 20 breaths per minute. If each breath has a volume of 310<br />

mL of air at 20°C <strong>and</strong> 0.997 atm, how many moles of air does a person inhale each day? If the density of air is<br />

1.19 kg/m 3 , what is the average molecular mass of air?<br />

20. Kerosene has a self-ignition temperature of 255°C. It is a common accelerant used by arsonists, but its<br />

presence is easily detected in fire debris by a variety of methods. If a 1.0 L glass bottle containing a mixture of<br />

air <strong>and</strong> kerosene vapor at an initial pressure of 1 atm <strong>and</strong> an initial temperature of 23°C is pressurized, at<br />

what pressure would the kerosene vapor ignite?<br />

A N S W E R S<br />

1.<br />

a. 7.05 × 10 −2 mol<br />

b. 3.78 × 10 −2 mol<br />

c. 0.2138 mol<br />

d. 3.4 × 10 −2 mol<br />

2.<br />

3.<br />

Saylor URL: http://www.saylor.org/books<br />

Saylor.org<br />

921

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