Putting Gasesto Work

Cracking under pressure

Pumps 1 ½” water stream 260 feet.

Gas: Alteration of Latin chaos space, chaos Date: 1779

The gas engine is one of the wonders of the 19th century. Now, within three years of the 20th century, it is a novel machine, eagerly sought by many people. It is thought by persons who have not studied its principles that it is a steam-engine, using gas or gasoline as fuel for the purpose of making steam. This is erroneous. Gas and gasoline in specific proportion with air are explosive material.

It is only a matter of time when the prejudice that, as usual, exists against any innovation, the ungrounded fear of explosions and other difficulties, will be overcome and the superiority of the gas engine over the wasteful steam engine and boiler will be established.

The unsightly smoke stacks, belching forth smoke and soot, will be relegated to the scrap heap. The atmosphere of our manufacturing cities will be as clear as that of the country.

In the next decade the steam engine will occupy the same relative position to the gas engine that the flint and steel now do to the lucifer match.

the tallow dip to the electric light...

...the stage coach to the modern electric street cars, and civilization will record another grand stride toward the millennium.

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V=0.5 , P=2

V=0.1, P=10

V=10, P=0.1

V=6 , P=5

V=3, P=10

V=30, P=2

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27 ºC = 300 K

27 ºC = 300 K

0 K

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27 ºC = 300 K

327 ºC = 600 K

327 ºC = 600 K

0 K

15 psi, 300 K

30 psi

3 psi

1 psi

600 K

60 K

20 K

15 psi, 2 L, 300 K30 psi

6 psi

3 psi

2 psi

600 K

60 K

60 K

20 K

2 L

1 L

2 L

1 L

1.4 x 1.4 = 2 doubles 2 x 2 = 2

1.5 x 1.33 = 2

• P is pressure measured in atmospheres. • V is volume measured in Liters• n is moles of gas present.• R is a constant that converts the units. It's value is

0.0821 atm•L/mol•K

• T is temperature measured in Kelvin.• Simple algebra can be used to solve for any of these

values. • P = nRT V = nRT n = PV T = PV R = nT• V P RT nR PV

• Pressure=1 atmosphere• Volume=1 Liter• n = 1 mole• R=0.0821• What is the temperature?

Facts:2 Liter bottle

¼ lb = 454 g ÷ 4 = 114g

PV = nRT or P = nRT

What pressure could be reached when ¼ lb of dry ice is placed in this 2 liter bottle? Temperature that night was 86 °F (30 °C)

VCO2= 12g/mol + 2*16g/mol = 44 g/mol

114 g = mol44 g

2.61 mol

What pressure could be reached when ¼ lb of dry ice is placed in this 2 liter bottle? Temperature that night was 86 °F (30 °C)

2.6 mol x 0.0821 atm*L x 303 Kmol*K

P =2.0 L

n R T

V

P = 32.3 atmospheres

32.3 atm = psi1 atm

47514.7 psi

• 760 mm of Hg• 760 torr• 29.9 in. of Hg• 1 Atmosphere• 14.7 lbs. per sq. in.• Temperature conversions: • Kelvin = Celsius + 273 • OC = (OF -32) x 5/9 • OF= OC x 9/5 + 32

CONVERSIONS

All Equal

Evangelista Torricelli

When a pressure cooker is used, whatWhen a pressure cooker is used, what

causes the increased pressure?causes the increased pressure?

PV=nRTPV=nRT P=P=nRTnRT VV

Temperature goes from 25Temperature goes from 25ooC to 100C to 100ooCC

Turn to Kelvin by adding 273 to CelsiusTurn to Kelvin by adding 273 to Celsius

297K to 373K 75K/297K=25% increase in pressure297K to 373K 75K/297K=25% increase in pressure

Temp C PSI mm Hg inches Hg0 0.089 5 0

25 0.458 24 150 1.779 92 4

100 14.700 760 30110 20.800 1075 42120 28.800 1489 59130 39.100 2021 80140 52.400 2709 107150 69.000 3567 140170 114.900 5940 234180 145.400 7517 296190 182.000 9410 370200 225.000 11633 458

75K / 297K= 25% 297K

373K

Water vapor pressure

0.000

50.000

100.000

150.000

200.000

250.000

0 100 200 300

Temperature Celsius

PS

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Series1

• You are on a camping trip and one tire has a slow leak. Finally it goes flat and you don’t have a spare tire. You suggest crushing some of the dry ice you had brought along and funneling it into the tire through the tire valve. How many grams of dry ice would you need to blow up a tire with a volume of 80 liters and pressure of 32 psi? Current temp is 25OC.

• Change 32 psi to atm and 25OC to Kelvin • 32 psi x 1 atm = 2.177 atm 14.7 psi• 25OC= 273+25=298 K• Solve PV=nRT for n (moles) n = PV

RT• n = 2.177 atm x 80 Liters • 0.0821 atm•L/mol•K x 298K• n = 7.118 moles > 7.118 mol x 44.01 g/mol = 313.3 g or 310 g• 310 g x 1 lbs per 453 grams = 0.68 lbs.

P1V1=n1RT1 P2V2=n2RT2

n1T1 n1T1 n2T2 n2T2

P1V1= R P2V2= R

n1T1 n2T2

P1V1= P2V2

n1T1 n2T2

• Molar mass = gRT • PV• 12. In 1984 in a village in the African nation of Cameroon,

1,700 people died from carbon dioxide poisoning when the nearby lake released huge amounts of CO2. As a early warning device, a pump could be designed to pump samples of air into a 4 liter container until the mass of the container grew by 22 grams. At that point a pressure reading could be taken as well as the temperature. Let’s say the pressure is 3.1 atmospheres and the temperature is 30OC (86OF). What molar mass would the device calculate?

• Plug in the values into the equation• Molar mass = 22 g x 0.0821 atm•L/mol•K x (273+30) K• 3.1 atm x 4 L• Molar mass = 44.13 g/mole