If 0.385 g of gas occupies a volume of 200 mL at -73 oC and 750 torr, what is the molecular mass of the gas?

a) 21.4
b) 32.0
c) 44.0
d) 48.0

Someone can help me this answer please..?

User Icon for DrBob222 DrBob222 answered
14 years ago

PV = nRT

Calculate n = number of moles.
Then n = grams/molar mass.
Calculate molar mass.

User Icon for Explain Bot Explain Bot answered
11 months ago

To find the molecular mass of the gas, we can use the ideal gas law equation:

PV = nRT

Where:
P = pressure (in atm)
V = volume (in liters)
n = number of moles
R = gas constant (0.0821 L·atm/(mol·K))
T = temperature (in Kelvin)

First, let's convert the given values to the appropriate units:
- The temperature -73 oC needs to be converted to Kelvin. The Kelvin temperature scale is obtained by adding 273.15 to the Celsius temperature, so -73 oC + 273.15 = 200.15 K.
- The volume 200 mL needs to be converted to liters. There are 1000 mL in a liter, so 200 mL / 1000 mL/L = 0.2 L.
- The pressure 750 torr needs to be converted to atm. There are 1 atm in 760 torr, so 750 torr / 760 torr/atm = 0.9868 atm.

Now we can substitute the values into the ideal gas law equation:

(0.9868 atm)(0.2 L) = (n)(0.0821 L·atm/(mol·K))(200.15 K)

Simplifying the equation:

0.19736 = (n)(0.0821)(200.15)
0.19736 = 16.862715n

Solving for moles (n):

n = 0.19736 / 16.862715
n ≈ 0.01168 moles

Next, we can calculate the molecular mass using the formula:

molecular mass = mass / moles

Given that the mass is 0.385 g, we can substitute these values:

molecular mass = 0.385 g / 0.01168 moles

Simplifying the equation:

molecular mass ≈ 32.999

So, the molecular mass of the gas is approximately 32.999 g/mol.

Comparing this value to the answer choices, we can see that the closest option is b) 32.0. Therefore, the correct answer is b) 32.0.