A sample of helium gas has a mass of 11.28 g. At STP (T = 25 C, P=101.3 kPa), the

Question

sample has a volume of 63.2 L. What is the molar volume (volume per mole) of this gas

at 32.2° C and 98.1 kPa?

Answer 1

A sample of helium gas has a mass of 11.28 g. At STP (T = 25 C, P=101.3 kPa), the

sample has a volume of 63.2 L. What is the molar volume (volume per mole) of this gas

at 32.2° C and 98.1 kPa?

Answer 2

To find the molar volume of the gas at the given conditions, we can use the ideal gas law:

PV = nRT

where P is the pressure, V is the volume, n is the amount of gas (in moles), R is the ideal gas constant, and T is the temperature (in kelvin).

First, we need to find the amount of gas (in moles) in the sample at STP. We can use the molar mass of helium to convert the mass to moles:

molar mass of helium = 4.003 g/mol

moles of helium = mass / molar mass = 11.28 g / 4.003 g/mol = 2.817 mol

Now we can use the molar volume of a gas at STP (which is approximately 22.4 L/mol) to find the volume of the sample in molar units:

volume in molar units = volume / molar volume at STP = 63.2 L / 22.4 L/mol = 2.82 mol

We can use this value, along with the given temperature and pressure, to find the molar volume at the new conditions:

V = nRT/P

V = (2.82 mol)(0.0821 L·atm/mol·K)(305.2 K) / (98.1 kPa)

V = 66.9 L/mol

Therefore, the molar volume of helium at 32.2°C and 98.1 kPa is approximately 66.9 L/mol.