A sample of a gas weighs 4.526g and has a volume of 890.0 mL at 645.0 torr and 29(degrees C). What is its molar mass?
Someone worked this for you about three pages ago. I'll try to find it and give you a link here.
http://www.jiskha.com/display.cgi?id=1301522559
how do you get the molar mass from the moles?
moles = grams/molar mass
You know moles and you know grams, solve for molar mass.
To determine the molar 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, let's convert the given temperature from degrees Celsius to Kelvin:
T(Kelvin) = T(Celsius) + 273
T(K) = 29 + 273 = 302K
Next, we need to convert the given pressure from torr to atmospheres:
1 atm = 760 torr
P(atm) = P(torr) / 760
P(atm) = 645.0 / 760 = 0.8487 atm
Now, we can rearrange the ideal gas law equation to solve for n (number of moles):
n = PV / RT
To get n, we need to convert the volume from mL to liters:
V(liters) = V(mL) / 1000
V(L) = 890.0 / 1000 = 0.890 L
Now, we can calculate n:
n = (0.8487) * (0.890) / (0.0821) * (302)
n ≈ 0.03071 moles
Next, we can calculate the molar mass (M) using the formula:
M = molar mass / n
Rearranging the equation:
molar mass = M * n
Given that the sample weight (m) is 4.526g, we can substitute the values in the formula:
molar mass = 4.526g / 0.03071moles
molar mass ≈ 147.36 g/mol
Therefore, the molar mass of the gas is approximately 147.36 g/mol.