Question

Henry's Law states that the quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility coefficient (its physical or chemical attraction for water), at a given temperature. Henry's Law: The volume of a gas (Vx) dissolved in a liter of water is Vx = (pX)*(SC), where pX is the partial pressure in atmospheres and SC is the solubility coefficient.

a) At 1 atm and 37 degrees Celsius, the solubility coefficient for oxygen is 0.024 ml O2/ml H2O. How much oxygen can dissolve in a liter of water at 37 degrees Celsius if the partial pressure of oxygen is 85 mm Hg =

b) At 1 atm and 20 degrees Celsius, the solubility coefficient for Carbon dioxide is 0.88 ml CO2/ml H2O at one atmosphere. How much CO2 can dissolve in a liter of water at 20 degrees Celsius if the partial pressure of CO2 is 38 mm Hg?

Answer 1

a)

Partial pressure $P_{O2}=\frac{85 \ mm \ Hg}{760 \ mm \ Hg}=0.1118 \ atm$

$V_{O2}=P_{O2} \times SC$

$V_{O2}=0.1118 \ atm \times \frac{0.024 \ ml \ O_2}{ml \ H_2O}$

$V_{O2}= \frac{ 0.002684 \ ml \ O_2}{ml \ H_2O}$

For 1 L (1000 mL of water)

$V_{O2}= \frac{ 0.002684 \ ml \ O_2}{ml \ H_2O} \times \frac{ 1000 \ mL \ H_2O}{ 1 \ L \ H_2O}$

$V_{O2}= \frac{ 2.68 \ ml \ O_2}{L \ H_2O}$

b)

Partial pressure $P_{CO2}=\frac{38 \ mm \ Hg}{760 \ mm \ Hg}=0.05 \ atm$

$V_{CO2}=P_{CO2} \times SC$

$V_{CO2}=0.05 \ atm \times \frac{0.88 \ ml \ CO_2}{ml \ H_2O}$

$V_{CO2}= \frac{ 0.044 \ ml \ CO_2}{ml \ H_2O}$

For 1 L (1000 mL of water)

$V_{CO2}= \frac{ 0.044 \ ml \ CO_2}{ml \ H_2O} \times \frac{ 1000 \ mL \ H_2O}{ 1 \ L \ H_2O}$

$V_{CO2}= \frac{ 44 \ ml \ CO_2}{L \ H_2O}$