TRO3_Lecture_11_mod

# According to boyles law what should happen to the

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According to Boyle’s law, what should happen to the volume of air in the lungs? Since the pressure is decreasing by a factor of 3, the volume will expand by a factor of 3, causing damage to internal organs. Always Exhale When Rising!! Tro's Introductory Chemistry, Chapter 11 30 Practice A Balloon Is Put in a Bell Jar and the Pressure Is Reduced from 782 torr to 0.500 atm. If the Volume of the Balloon Is Now 2780 mL, What Was It Originally? (1 atm = 760 torr) Temperature Scales Celsius Kelvin Fahrenheit -273°C -269°C -183°C -38.9°C 0°C 100°C 0 K 4 K 90 K 234.1 K 273 K 373 K -459 °F -452°F -297°F -38°F 32°F 212°F Absolute Zero BP Helium BP Oxygen BP Mercury MP Ice BP Water 0 R 7 R 162 R 421 R 459 R 671 R Rankine

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1/8/2014 11 Tro's Introductory Chemistry, Chapter 11 32 Gas Laws and Temperature Gases expand when heated and contract when cooled, so there is a relationship between volume and temperature. Gas molecules move faster when heated, causing them to strike surfaces with more force, so there is a relationship between pressure and temperature. In order for the relationships to be proportional, the temperature must be measured on an absolute scale. When doing gas problems, always convert your temperatures to kelvins. K = °C + 273 & °C = K - 273 °F = 1.8 °C + 32 & °C = 0.556(°F-32) Tro's Introductory Chemistry, Chapter 11 33 Standard Conditions Common reference points for comparing. Standard pressure = 1.00 atm. Standard temperature = 0 °C. 273 K. STP. Tro's Introductory Chemistry, Chapter 11 34 Volume and Temperature In a rigid container, raising the temperature increases the pressure. For a cylinder with a piston, the pressure outside and inside stay the same. To keep the pressure from rising, the piston moves out increasing the volume of the cylinder. As volume increases, pressure decreases.
1/8/2014 12 Tro's Introductory Chemistry, Chapter 11 35 Volume and Temperature, Continued Because the hot air in the balloon is less dense than the surrounding air, it rises. As a gas is heated, it expands. This causes the density of the gas to decrease. Tro's Introductory Chemistry, Chapter 11 36 Charles’s Law Volume is directly proportional to temperature. Constant P and amount of gas. Graph of V vs. T is a straight line. As T increases, V also increases. Kelvin T = Celsius T + 273. V = constant x T . If T is measured in kelvin. 2 2 1 1 T V T V 37 Charle's Law & Absolute Zero 0 0.1 0.2 0.3 0.4 0.5 0.6 -300 -250 -200 -150 -100 -50 0 50 100 150 Temperature, °C Volume, L Volume (L) of 1 g O2 @ 1500 torr Volume (L) of 1 g O2 @ 2500 torr Volume (L) of 0.5 g O2 @ 1500 torr Volume (L) of 0.5 g SO2 @ 1500 torr

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1/8/2014 13 Tro's Introductory Chemistry, Chapter 11 38 Absolute Zero Theoretical temperature at which a gas would have zero volume and no pressure. Kelvin calculated by extrapolation. 0 K = -273.15 °C = -459 °F = 0 R.
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