Question

What is the molar mass of a gas with a density of 3.50 g/L at a

temperature of 345 K and a pressure of 0.950 atm? (Write your
answer whole number e.g. 345)
g/mol

Answer 1

• 104 g/mol

Step-by-step explanation:

Use the ideal gas equation:

`pV=nRT`

Where:

• p is pressure: 0.950atm
• V is volume: unknown
• n is number of moles: unknown
• R is the universal constat of gases: 0.08206 atm.liter/ (K.mol)
• T is the absolute temperature: 345K

Use the molar mass of the gas to include the density in the formula:

• molar mass = mass in grams / number of moles

• ⇒ mass in grams = number of moles × molar mass

• density = mass in grams / volume

• ⇒ density = number of moles × molar mass / volume

• density = (n/V) × molar mass

• ⇒ n/V = density / molar mass

Clear n/V from the gas ideal equation and subsittute with density/molar mass:

• n/V = p/(RT)

• density / molar mass = n/V

• density/molar mass = p/(RT)

• molar mass = density × RT / p

Now you can subsitute the data:

molar mass = (3.50g/liter) × 0.08206 atm.liter/(K.mol) × 345K / 0.950 atm

• molar mass = 104.3 g/mol

• Round to the nearest whole number: 104g/mol ← answer