Answer:
121 g/mol
Step-by-step explanation:
To find the molar mass, you first need to calculate the number of moles. For this, you need to use the Ideal Gas Law. The equation looks like this:
PV = nRT
In this equation,
-----> P = pressure (atm)
-----> V = volume (L)
-----> n = moles
-----> R = constant (0.0821 L*atm/mol*K)
-----> T = temperature (K)
Because density is comparing the mass per 1 liter, I am assuming that the system has a volume of 1 L. Before you can plug the given values into the equation, you first need to convert Celsius to Kelvin.
P = 1.00 atm R = 0.0821 L*atm/mol*K
V = 1.00 L T = 25.0. °C + 273.15 = 298.15 K
n = ? moles
PV = nRT
(1.00 atm)(1.00L) = n(0.0821 L*atm/mol*K)(298.15 K)
1.00 = n(0.0821 L*atm/mol*K)(298.15 K)
1.00 = (24.478115)n
0.0409 = n
Now, we need to find the molar mass using the number of moles per liter (calculated) and the density.
0.0409 moles ? grams 4.95 grams
---------------------- x ------------------ = ------------------
1 L 1 mole 1 L
? g/mol = 121 g/mol
**note: I am not 100% confident on this answer