A 1-L flask is filled with 1.25g of argon at 25C . A sample of ethane vapor is added to the same flask until the total pressure is 1.45amt .What is the partial pressure of argon, Par, in the flask?
Use PV = nRT to calculate the partial pressure of the argon gas.
To find the partial pressure of argon (Par) in the flask, we need to use the ideal gas law and Dalton's law of partial pressures.
Step 1: Convert the mass of argon to moles.
To convert the mass of argon (1.25g) to moles, we need to know the molar mass of argon. The molar mass of argon (Ar) is approximately 39.95 g/mol. We can use the formula:
moles of argon = mass of argon / molar mass of argon
moles of argon = 1.25g / 39.95 g/mol
moles of argon ≈ 0.0313 mol (rounded to four decimal places)
Step 2: Use the ideal gas law to find the initial pressure of argon.
The ideal gas law equation is:
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 in Kelvin.
Since we have a 1-L flask filled with argon at 25°C (298 K), the volume (V) is 1 L, the number of moles (n) is 0.0313 mol (from step 1), and R is 0.0821 L·atm/(mol·K).
Now we can rearrange the ideal gas law equation to solve for P:
P = (nRT) / V
P = (0.0313 mol)(0.0821 L·atm/(mol·K))(298 K) / 1 L
P ≈ 0.775 atm (rounded to three decimal places)
Step 3: Use Dalton's law of partial pressures to find the partial pressure of argon.
According to Dalton's law, the total pressure (1.45 atm) is the sum of the partial pressures of all the gases present. Therefore, the partial pressure of argon (Par) can be calculated as:
Par = Total pressure - Pressure of other gases
Par = 1.45 atm - Pressure of other gases
Since we only have argon and ethane in the flask, and we know the total pressure is 1.45 atm, we can subtract the partial pressure of ethane from the total pressure to find the partial pressure of argon:
Par = 1.45 atm - Pressure of ethane
Note: We need more information to calculate the pressure of ethane. If we know the number of moles or the mass of ethane added, we can calculate its partial pressure using the same method as step 1 and step 2.