Someone can help me please?
A gas sample weighing 0.528 g is collected in a flask having a volume of 126 mL. At 75 degrees celcius the pressure of the gas is 75 torr. The molecular mass of the gas is closest to which one of the following?
Use PV = nRT
Calculate n.
Then n = grams/molar mass. Calculate molar mass.
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Someone can help me please?
A gas sample weighing 0.528 g is collected in a flask having a volume of 126 mL. At 75 degrees celcius the pressure of the gas is 750 torr. The molecular mass of the gas is closest to which one of the following?
PV=nRT Thanks, DrBob222
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To find the molecular mass of the gas, we 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 in Kelvin.
First, we need to convert the given temperature from Celsius to Kelvin:
T(K) = T(C) + 273.15
T(K) = 75 + 273.15 = 348.15 K
Now we can rearrange the ideal gas law equation to solve for n, the number of moles:
n = PV / RT
Next, we need to convert the pressure from torr to atm, as the ideal gas constant R has units of atm.
1 atm = 760 torr
So, the pressure in atm can be calculated as:
P(atm) = P(torr) / 760
P(atm) = 75 / 760 = 0.0987 atm (rounded to four decimal places)
We also need to convert the volume from milliliters to liters, as the ideal gas law equation requires volume in liters:
V(L) = V(mL) / 1000
V(L) = 126 / 1000 = 0.126 L
Now, let's substitute the values into the equation:
n = (0.0987 atm) * (0.126 L) / (0.0821 atm * L / mol * K) * (348.15 K)
Simplifying the equation:
n = 0.1237 / 28.57
n ≈ 0.00433 moles
Finally, to find the molecular mass of the gas, we divide the mass of the gas sample (0.528 g) by the number of moles (0.00433 mol):
molecular mass = mass of gas sample / number of moles
molecular mass = 0.528 g / 0.00433 mol
molecular mass ≈ 122 g/mol
Therefore, the molecular mass of the gas is closest to 122 g/mol.