Henry’s law constant for CO2 in water is 1.67x108 Pa at 298 K. Calculate the quantity of CO2 in 500 mL of soda water when packed under 2.5 atmCO2 pressure at 298 K.


According to Henry's law,


"At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid."


Stated as,


p = KHx


Where,


P = partial pressure of the solute above the solution


KH = Henry's constant


x = concentration of the solute in the solution


Given,


KH = 1.67x108 Pa


PCO2 2.5 atm = 2.5 × 1.01325 × 105Pa


According to Henry's law,


p = KHx




x = 0.00152


In 500 ml of soda water there is 500 ml of water (neglecting soda)


Mole of water =


= 27.78 mol


Now,


x =


nCO2 = x nH2O


= 0.00152 × 27.78


= 0.042 mol


Hence, quantity of CO2 in 500mL of soda water 0.042 × 44 = 1.848 g


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