Help With Gas/Liquid Pressure/Volume

[Brzostek]

1. Assume that a high dissolved oxygen level is 10 mg/L. If you have a liter (L) of water and removed all of the oxygen from it what volume would it occupy? (Use the ideal gas law and assume that P = 1 atm = 1 bar and that temperature is 25 C).



2. PV = nRT



3. Don't know how to use this equation with a gas and liquid.

 

[Andrew Mason]

1. Assume that a high dissolved oxygen level is 10 mg/L. If you have a liter (L) of water and removed all of the oxygen from it what volume would it occupy? (Use the ideal gas law and assume that P = 1 atm = 1 bar and that temperature is 25 C).

So how many milligrams of O₂ would be removed (assume there are 10 mg/L dissolved in the water)? How many moles of O₂ is that? How much volume will that amount of O₂ occupy at 1 atm = 101325 Pa. and 25C (Hint: use PV=nRT. What is the temperature in K?)?


AM

 

[tomcue]

I can provide some guidance on how to use the ideal gas law equation in this scenario. The ideal gas law, PV = nRT, relates the pressure (P), volume (V), number of moles (n), and temperature (T) of a gas. In this case, we are dealing with a gas (oxygen) dissolved in a liquid (water), so we need to make a few adjustments.

First, we need to convert the dissolved oxygen level from mg/L to moles/L. This can be done by dividing the given value of 10 mg/L by the molar mass of oxygen, which is approximately 32 g/mol. This gives us 0.3125 mol/L.

Next, we need to consider the fact that the oxygen is dissolved in water, which will exert its own pressure on the gas. This is known as the partial pressure of the gas. In this case, we can assume that the partial pressure of oxygen is equal to the atmospheric pressure, which is 1 atm or 1 bar.

Now, we can rearrange the ideal gas law to solve for volume (V).

V = nRT/P

Plugging in the values we have, we get: V = (0.3125 mol/L)(0.0821 L*atm/mol*K)(298 K)/(1 atm) = 7.66 L

Therefore, if we were to remove all of the oxygen from 1 L of water, it would occupy a volume of 7.66 L. It's important to note that this is an estimate, as the ideal gas law assumes ideal conditions and may not be entirely accurate for a gas dissolved in a liquid. However, it can give us a general idea of the volume that the gas would occupy.