Given:
Henry's constant for CO2 in water,
KH=1.67×108 Pa at 298 K
pCO2=2.5! atm=2.5×101325 Pa
According to Henry's Law,
pCO2=KH+χCO2
By putting the values, we get,
2.5×101325=1.67×108×χCO2
⇒χCO2=2.5×1013251.67×108=1.517×10−3
Moles of CO2
Molar mass of water H2O
=1×2+16×1
=18gmol−1
Mass of 500mL of water
=500g (density of water)=1gcm−3
Therefore, number of moles of water (H2O) in 500mL of water,
=50018=27.78mol
Now, since nCO2 is very small, we can write
χCO2=nCO2nH2O+nCO2≈nCO2nH2O
By putting the values, we get,
nCO2=1.517×10−3×27.78
nCO2=42.14×10−3mol
Mass of CO2
Molar mass of CO2
=12+2×16
44gmol−1
Therefore, mass of CO2 present
=molar mass of CO2×nCO2
=44×42.14×10−3
=1.854g
Final Answer:
The quantity of CO2 in 500mL of soda water is 1.854 g.