We cannot determine the molar mass of the gas at 125 degrees Celsius directly, but we can determine the molar mass of the gas at STP and then apply that value to the given conditions at 125 degrees Celsius. Here's how:
At STP (Standard Temperature and Pressure), the temperature is 0 degrees Celsius (273.15 K) and the pressure is 1 atm.
1. Determine the number of moles of the gas using the ideal gas law:
PV = nRT
We know the following at STP:
P = 1 atm
V = 750 mL = 0.750 L (conversion)
R = 0.0821 L*atm/mol*K (ideal gas constant)
T = 273.15 K
Plug in the values to find the number of moles (n):
(1 atm) * (0.750 L) = n * (0.0821 L*atm/mol*K) * (273.15 K)
Solve for n:
n = (1 atm * 0.750 L) / (0.0821 L*atm/mol*K * 273.15 K)
n ≈ 0.03271 moles
2. Calculate the molar mass (MM) of the gas:
MM = mass of the sample / number of moles
MM = 2.15 g / 0.03271 moles
MM ≈ 65.75 g/mol
Now we have the molar mass of the gas (65.75 g/mol) at STP, assuming that the molar mass does not change under different conditions, we can report that under 125 degrees Celsius, the molar mass of the gas is also approximately 65.75 g/mol.
If a 2.15-g sample of gas occupies 750. mL at STP, what is the molar mass of the gas at 125 degrees celcuis
1 answer
1 answer