A 1.00L sample of a gas has a mass of 1.92g at STP. What is the molar mass of the gas?
(This is a question on my chemistry worksheet, and I can't find the answer in my book.)
Multiply the mass by 22.4, and you have the molar mass (mass in 22.4 liters).
43.0 g/mol
thank you! that is what I did, but I wasn't sure.
To find the molar mass of the gas, we need to use the ideal gas law. The ideal gas law equation is given as:
PV = nRT
Where:
P = Pressure
V = Volume
n = Number of moles
R = Ideal gas constant
T = Temperature
In this case, we have a sample of gas at STP, which means the pressure (P) and temperature (T) can be fixed values:
P = 1 atm (standard atmospheric pressure)
T = 273.15 K (standard temperature)
The volume (V) is given as 1.00 L. Now, we can rearrange the ideal gas law equation to solve for the number of moles (n):
n = PV / RT
Given the mass of the gas, we can use the molar mass formula to find the number of moles:
n = m / M
Where:
m = mass of the gas
M = molar mass of the gas
In this case, the mass of the gas is given as 1.92 g. We can now solve for the molar mass (M):
M = m / n
Let's substitute the values we have into the equation:
M = 1.92 g / (PV / RT)
Since we have the values for P, V, R, and T at STP, we can plug them into the equation:
M = 1.92 g / (1 atm * 1.00 L / (0.0821 L·atm/mol·K * 273.15 K))
Now, we can calculate the molar mass:
M = 1.92 g / (0.0821 L·atm/mol·K * 273.15 K)
M = 1.92 g / (22.4 L·atm/mol·K)
M = 0.086 g/mol
Therefore, the molar mass of the gas is 0.086 g/mol.