Mechanics of Breathing

Timberlake, Chemistry 7th Edition, page 254

Air Pressure

Water pressure increasesdue to greater fluid aboveopening.

“One Minute Left”

SCUBA Diving

• Self Contained Underwater Breathing Apparatus• Rapid rise causes “the bends”

– Nitrogen bubbles out of blood

rapidly from pressure decrease

Must rise slowly to the surface to avoid the “bends”.

Exchange of Blood Gases

Timberlake, Chemistry 7th Edition, page 273

Solubility of Carbon Dioxide in Water

Temperature Pressure Solubility of CO2

Temperature Effect

0oC 1.00 atm 0.348 g / 100 mL H2O20oC 1.00 atm 0.176 g / 100 mL H2O40oC 1.00 atm 0.097 g / 100 mL H2O60oC 1.00 atm 0.058 g / 100 mL H2O

Pressure Effect

0oC 1.00 atm 0.348 g / 100 mL H2O0oC 2.00 atm 0.696 g / 100 mL H2O0oC 3.00 atm 1.044 g / 100 mL H2O

Notice that higher temperatures decrease the solubility and that higher pressures increase the solubility.

Corwin, Introductory Chemistry 4th Edition, 2005, page 370

Vapor Pressure of Water Temp. Vapor Temp. Vapor Temp. Vapor (oC) Pressure (oC) Pressure (oC) Pressure (mm Hg) (mm Hg) (mm Hg)

0 4.6 21 18.7 35 41.2

5 6.5 22 19.8 40 55.3

10 9.2 23 21.1 50 71.9

12 10.5 24 22.4 55 92.5

14 12.0 25 23.8 35 118.0

16 13.6 26 25.2 40 149.4

17 14.5 27 26.7 40 233.7

18 15.5 28 28.4 55 355.1

19 16.5 29 30.0 35 525.8

20 17.5 30 31.8 40 760.0

Corwin, Introductory Chemistry 4th Edition, 2005, page 584

Solventmolecules

Nonvolatilesolutemolecules

Solventmolecules

Nonvolatilesolutemolecules

Henry’s LawHenry’s law states that the solubility of oxygen gas is proportional

to the partial pressure of the gas above the liquid.

EXAMPLE:

Calculate the solubility of oxygen gas in water at 25oC and a partial pressureof 1150 torr. The solubility of oxygen in water is 0.00414 g / 100 mL at 25oC and 760 torr.

0.00414 g / 100 mL1150 torr

760 torr= 0.00626 g / 100 mL

solubility x pressure factor = new greater solubility

Corwin, Introductory Chemistry 4th Edition, 2005, page 370

Note: 1 torr = 1 mm Hg