We can solve this problem by using Henry's law.
Henry's law states that the amount of dissolved gas is proportional to its partial pressure.
[tex]C=kP[/tex]
C is the solubility of a gas.
k is Henry's law constant.
P is the partial pressure of the gas.
We can calculate the constant from the first piece of information and then use Henry's law to calculate solubility in open drink.
0.12=4k
k=0.03
Now we can calculate the solubility in open drink.
[tex]C_o=kP_o
[/tex]
[tex]C_o=0.03 \cdot 3\cdot 10^{-4}=0.09\cdot 10^{-4} \frac{mol}{L} [/tex]
Now we need to convert it to g/L. One mol of CO2 is 44.01g.
The final answer is:
[tex]C_o=0.09\cdot 10^{-4}\cdot 44,01=3.4\cdot 10^{-4} \frac{g}{L} [/tex]
