Equilibrium concentration of co2 in beer

In summary, the absolute pressure is equal to the gauge pressure plus the atmospheric pressure. The gauge pressure is equal to 1.29 bar or 129,000 Pa, while the atmospheric pressure is equal to 1.01x10^5 Pa. The Henry's law constant is 116 x 10^6 Pa, not 116 x 10^3 Pa. Using this correct constant, the mole fraction of CO2 is 0.0019 and the amount in the 1L of beer is 3.25 g.
  • #1
sci0x
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5
Homework Statement
Beer keg, stored at 10 deg C, is pressurized by gas 70% vol/vol CO2 : 30% N2. If the top pressure of the mixed gas is 1.29 bar guage, calculate the equilibrium conc of CO2 in beer (gl-1) assuming that the hydrostatic effect of pressure on CO2 conc of the beer in the keg can ben neglected and the beer has the same density of water

Henrys constant for CO2 at 10 deg C is 116 x 10^3 Pa mole fraction-1
Atm pressure is 1.01 bar absolute
1 bar = 10^5 Pa
Density of water at 10 deg C = 1000kgm-3
Relative mol weight of CO2 and H2O are 44 and 18 respectively
Relevant Equations
Henrys law P=KhC
Absolute pressure is gauge pressure + atmos press

Guage press = 1.29 bar G
1 bar = 10^5 Pa
1.29 bar = 129,000 Pa

Atmos Pres = 1.01x10^5 Pa

Absolute pressure = 230,000 Pa

Henrys law: P=KhC
230000Pa = (116x10^3Pa)C
1.98 mole fraction =C
70% CO2 = 1.387 mole fraction

44g Co2 in 1 mole
61.07g in 1.89mole

1L beer = 1000kgm-3 ÷ 18 = 55.5g

55.5g x 61.07g CO2
= 3389.33 g/L

Please confirm if this is correct
 
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  • #2
Do you really think the mole fraction of CO2 is greater than 1? The Henry's law constant is not 116 x 10^3 Pa. It is 116 x 10^6 Pa.
 
  • #3
Updating henrys law constant:

Henrys law: P=KhC
230000Pa = (116x10^6Pa)C
0.0019 mole fraction =C
70% CO2 = 1.33x10^-3 mole fraction

44g Co2 in 1 mole
0.05852g CO2 in 1.33x10^-3 mole

1L beer = 1000kgm-3 ÷ 18 = 55.5g

55.5g x 0.05852g CO2
= 3.247 g/L
 
  • #4
That should be 55.5 moles of beer in a liter, not grams. Moles CO2 in a liter = 0.00133 x 55.5 = 0.0738 moles/liter

0.0738 moles/liter x 44 g/mole = 3.25 g/l
 
  • #5
Thanks Chester
 

1. What is the equilibrium concentration of CO2 in beer?

The equilibrium concentration of CO2 in beer is typically between 2.2-2.8 volumes, or 4-6 grams per liter. This means that for every liter of beer, there are 4-6 grams of CO2 dissolved in it.

2. How does the equilibrium concentration of CO2 in beer affect its taste?

The equilibrium concentration of CO2 in beer is a crucial factor in determining its taste. It affects the carbonation level, which can greatly impact the mouthfeel, aroma, and overall flavor of the beer. Too much CO2 can make the beer taste overly carbonated and sharp, while too little can make it taste flat and dull.

3. What factors can influence the equilibrium concentration of CO2 in beer?

The equilibrium concentration of CO2 in beer can be influenced by several factors, including temperature, pressure, and the type of beer. Higher temperatures and lower pressures result in lower equilibrium concentrations of CO2, while lower temperatures and higher pressures result in higher concentrations. Different beer styles also have different equilibrium concentrations of CO2, as some styles are naturally more carbonated than others.

4. How is the equilibrium concentration of CO2 in beer measured?

The equilibrium concentration of CO2 in beer can be measured using a device called a carbonation tester, which measures the volume of CO2 in the beer. This is typically done by taking a sample of the beer and using the tester to determine the amount of CO2 present. Brewers can also use mathematical calculations based on temperature and pressure to estimate the equilibrium concentration of CO2.

5. Why is it important to maintain the equilibrium concentration of CO2 in beer?

Maintaining the proper equilibrium concentration of CO2 in beer is crucial for ensuring a consistent and enjoyable drinking experience. Too much or too little CO2 can significantly impact the taste and quality of the beer. Additionally, the equilibrium concentration of CO2 can affect the stability and shelf life of the beer, as well as its appearance and foam retention.

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