What is the molecular weight of a gas if 500 mL weighs 10 g at -23 °C and 380 torr?

To solve this problem, we will use the Ideal Gas Law, which is 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, we need to convert all our units to the standard units for this equation.

1. Convert the volume from mL to L: 500 mL = 0.5 L
2. Convert the pressure from torr to atm: 380 torr = 380/760 atm = 0.5 atm
3. Convert the temperature from Celsius to Kelvin: -23 °C = -23 + 273.15 = 250.15 K

Next, we can calculate the number of moles (n) using the Ideal Gas Law rearranged to solve for n: n = PV/RT

n = (0.5 atm * 0.5 L) / (0.0821 Latm/Kmol * 250.15 K) = 0.0121 mol

Finally, we can calculate the molar mass (M) of the gas using the formula M = mass/n

M = 10 g / 0.0121 mol = 826.45 g/mol

So, the molecular weight of the gas is approximately 826.45 g/mol.