Question

Henry 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 atm CO₂ Pressure At 298 K ?

Answer 1

According to Henry's law, p_CO2 = K_Hx

Here x is the mole fraction of carbon dioxide in the carbon dioxide water mixture.

p_CO2 = 2.5 atm = 2.5 * 1.01325 * 10⁵ Pa = 2.533125 * 10⁵ Pa

x = mole fraction = 2.533125 * 10⁵/ 1.67 * 10⁸ = 0.00152

x = moles of CO₂/(moles of CO₂ + moles of H₂O) ≈ moles of CO₂/moles of H₂O as mole of CO₂ are negligible in comparison to the number of moles of water

500 ml of water = 500g of water = 500/18 = 27.78 moles of water.

So, moles of CO₂/27.78 = 0.00152 or moles of CO₂ = 0.042 moles.
Hence the amount of CO₂ in 500 ml of soda water is 0.042 * 44 = 1.848 g.