Question

Suppose the total pressure in a bottle of soda water before it is opened is 40 psig (http://hypertextbook.com/facts/2000/SeemaMeraj.shtml) and that the gas mixture is 75% CO2 and 25% other gases. The temperature is 10°C. The Henry’s Law constant is 0.104x104 atm.

a) If the system is in equilibrium, how much CO2 is dissolved in the soda? (For this problem,ignore reactions between the CO2 and the water.) I know the answer is about 6500 mg/L but I'm having trouble finding the steps to get there!

b) Calculate the new equilibrium concentration when the bottle is opened. The volumetric fraction of CO2 in the normal atmosphere is 358 ppmv. Knowing this, explain why the CO2 acts as it does when the bottle is opened.

PLEASE ANSWER BOTH PARTS OR I WILL NOT "THUMBS UP" YOUR ANSWER!

Answer 1

1. Henry's law is one of the gas laws formulated by William Henry in 1803 and states: "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." An equivalent way of stating the law is that the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid:

You may apply this formula. You might be having trouble with the conversion factors. The constant must be Molar/atm. As the given pressure is in atm. The conversion factor is 1 atm = 14.7 psig. Then the concentration is given at molar of CO2, you must convert from molar to mg of CO2.

2. as ppvm is ml/m3 this means there are 358 ml of CO2 per 1000000ml of air. Converting from ml to grams we get: 0.00075 kgCO2/m3