A 5.00 liter sample of gas measured at 27.0°C and 1.25 atm of pressure has a mass of 10.13 g. What is the molecular weight of the gas in u?

Question

Quizplus · Accepted Answer

The molecular weight of the gas can be calculated using the ideal gas law equation, 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, convert the temperature to Kelvin: 27.0°C + 273.15 = 300.15 K. Then, solve for n (moles of gas) using the ideal gas law: n = PV / RT. Substituting the given values and using R = 0.0821 L·atm/(mol·K), n = (1.25 atm)(5.00 L) / (0.0821 L·atm/(mol·K) * 300.15 K) = 0.253 mol. The molecular weight (M) is the mass of the gas divided by the number of moles: M = mass / n = 10.13 g / 0.253 mol = 40.0 g/mol, which is approximately 39.9 u.

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