A sample of a gas weighs 4.526g and has a volume of 890.9 mL at 645.0 torr and 29(degrees C). What is its molar mass?
I just need help setting this up!
First You convert 645.0 torr to atm, and also mL to L. You use PV=nRT, to find the number of moles.
Then you use the number of moles to get the molar mass. mol= mass/molar mass
To solve this problem, you'll need to use the ideal gas law equation:
PV = nRT
where:
P = pressure (in torr)
V = volume (in liters)
n = number of moles
R = ideal gas constant (0.0821 L·atm/mol·K or 62.36 torr·L/mol·K)
T = temperature (in Kelvin)
First, convert the given temperature from degrees Celsius to Kelvin by adding 273.15:
T = 29°C + 273.15 = 302.15 K
Next, convert the given volume in mL to liters:
V = 890.9 mL ÷ 1000 = 0.8909 L
Now, rearrange the ideal gas law equation to solve for the number of moles (n):
n = PV / RT
Substitute in the given values:
n = (645.0 torr) * (0.8909 L) / [(62.36 torr·L/mol·K) * (302.15 K)]
Now, calculate n:
n = 19.1159 / 18766.2122 ≈ 0.0010197 mol
The number of moles, n, represents the number of moles of the gas present in 4.526 g. To find the molar mass, divide the mass (in grams) by the number of moles:
Molar mass = mass / moles
Molar mass = 4.526 g / 0.0010197 mol ≈ 4446.36 g/mol
Therefore, the molar mass of the gas is approximately 4446.36 g/mol.