A sample of methane gas, CH4, was collected over water at 25.0 ºC and 730. torr. The volume of the wet gas is 4.64 L. What will be the volume of the dry methane at standard pressure?
I see MANY posts. Is this a homework dump?
Ptotal = pH2O + pCH4
Ptotal = 730 torr
pH2O = look up vapor pressure H2O @ 25 C. If it isn't in torr (mm Hg) convert so that both pressures are in the same units.
Solve for pCH4 of the dry gas.
Then use PV = nRT to solve for the volume @ STP.
What do YOU think it is Dr. Bob? You obviously know it is or you wouldn't have asked that. Come onnn 🤦♀️
Thank you Ok ummm.......... Oh Hi! I needed a second reminder.
Uhh yw ig.
To find the volume of the dry methane at standard pressure, we need to use the ideal gas law equation: PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature.
First, we need to determine the number of moles of methane gas. We can use the ideal gas law equation to rearrange it to solve for n:
n = PV / RT
The pressure is given as 730. torr, which needs to be converted to standard pressure units (1 atm = 760 torr). So, the pressure in atm will be 730. torr / 760 torr/atm = 0.961 atm.
The temperature is given as 25.0 ºC, which needs to be converted to Kelvin (K = ºC + 273.15). So, the temperature in Kelvin will be 25.0 ºC + 273.15 = 298.15 K.
Now, we can substitute these values into the equation to find the number of moles:
n = (0.961 atm) * (4.64 L) / [(0.0821 L.atm/mol.K) * (298.15 K)]
n ≈ 0.198 moles
Since the chemical formula of methane is CH4, it means that there is one mole of methane for every mole of gas. Therefore, the number of moles of dry methane will also be 0.198 moles.
Now, we need to find the volume of the dry methane at standard pressure. At standard pressure (1 atm), we can assume that gases behave ideally. We can use the ideal gas law equation to find the volume:
V = nRT / P
Substituting the values, we get:
V = (0.198 moles) * (0.0821 L.atm/mol.K) * (273.15 K) / (1 atm)
V ≈ 4.20 L
Therefore, the volume of the dry methane gas at standard pressure will be approximately 4.20 L.