A mixture of He and O2 is placed in a 4.00L flask at 32 degrees Celsius. The partial pressure of the He is 2.7 atm and the partial pressure of the O2 is 1.4 atm. What is the mole fraction of O2??
I don't understand how to do this.
mole fraction O2 = partial pressure O2/total pressure
mole fraction He = partial pressure He/total pressure.
And you thought chemistry was hard.
To determine the mole fraction of O2 in the mixture, you can use the following formula:
Mole fraction of O2 = (Partial pressure of O2) / (Total pressure of the mixture)
Given that the partial pressure of O2 is 1.4 atm and the total pressure of the mixture is the sum of the partial pressures of each component (He and O2), which is (2.7 atm + 1.4 atm = 4.1 atm).
Using the formula, we can calculate the mole fraction of O2 as follows:
Mole fraction of O2 = 1.4 atm / 4.1 atm = 0.341
So, the mole fraction of O2 in the mixture is approximately 0.341.
To find the mole fraction of O2 in the mixture, you need to first understand what mole fraction is.
Mole fraction (χ) is a way to express the amount of one component in a mixture relative to the total amount of all components in that mixture. It is calculated by dividing the moles of a specific component by the total moles in the mixture.
To solve this problem, you can follow these steps:
Step 1: Convert the partial pressures of He and O2 to moles.
- To convert from partial pressure to moles, you can 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 ideal gas constant, and T is the temperature.
- Rearrange the equation to solve for n: n = PV / RT.
- Plug in the given values for each gas to calculate the number of moles.
Step 2: Calculate the total moles in the mixture by summing the moles of each gas.
- Add the moles of He and O2 to get the total moles in the mixture.
Step 3: Calculate the mole fraction of O2.
- Divide the moles of O2 by the total moles in the mixture to get the mole fraction of O2.
Let's go through the calculations:
Step 1: Convert the partial pressures to moles.
- For He:
n_He = (P_He * V) / (R * T)
n_He = (2.7 atm * 4.00 L) / (0.0821 atm·L/mol·K * 305 K)
n_He ≈ 0.347 mol (rounded to three decimal places)
- For O2:
n_O2 = (P_O2 * V) / (R * T)
n_O2 = (1.4 atm * 4.00 L) / (0.0821 atm·L/mol·K * 305 K)
n_O2 ≈ 0.181 mol (rounded to three decimal places)
Step 2: Calculate the total moles in the mixture.
- Total moles = n_He + n_O2
- Total moles ≈ 0.347 mol + 0.181 mol ≈ 0.528 mol (rounded to three decimal places)
Step 3: Calculate the mole fraction of O2.
- Mole fraction of O2 = n_O2 / Total moles
- Mole fraction of O2 ≈ 0.181 mol / 0.528 mol ≈ 0.343 (rounded to three decimal places)
Therefore, the mole fraction of O2 in the mixture is approximately 0.343.