Physics 410
Spring 2014
HW#3
Due Wednesday, 11 February 2014
1. At 273K and 1.00 X 10-2 atm the density of a gas is 1.24 X 10-5 g/cm3. Find the
vrms of the molecules, find the molecular weight of the gas, and identify the gas.
2. Determine the average value of the translational kinetic energy of a single molecule
in an ideal gas at 0.0oC and 100oC. Express your answers in J and in eV (1 eV =
1.6 × 10-19 J. What is the total translational kinetic energy of one mole of ideal gas
molecules at these temperatures (in J)?
3. The (constant volume) specific heat of sulfur hexafluoride (SF6) is approximately
89 J/mol∙K. Estimate the number of degrees of freedom available to each molecule,
and speculate where these degrees of freedom come from.
4. Continuing with our homework exploration of the 2-D ideal gas, determine
a) an expression for the (constant volume) heat capacity of a 2-D monoatomic
ideal gas in terms of the ideal gas constant R.
b) an expression for the (constant volume) heat capacity of a 2-D diatomic ideal
gas in terms of the ideal gas constant R. Assume that vibrational and rotational
degrees of freedom are energetically accessible.
Physics 410
Spring 2014
HW#3
Due Wednesday, 11 February 2014
1. At 273K and 1.00 X 10-2 atm the density of a gas is 1.24 X 10-5 g/cm3. Find the
vrms of the molecules, find the molecular weight of the gas, and identify the gas.
2. Determine the average value of the translational kinetic energy of a single molecule
in an ideal gas at 0.0oC and 100oC. Express your answers in J and in eV (1 eV =
1.6 × 10-19 J. What is the total translational kinetic energy of one mole of ideal gas
molecules at these temperatures (in J)?
3. The (constant volume) specific heat of sulfur hexafluoride (SF6) is approximately
89 J/mol∙K. Estimate the number of degrees of freedom available to each molecule,
and speculate where these degrees of freedom come from.
4. Continuing with our homework exploration of the 2-D ideal gas, determine
a) an expression for the (constant volume) heat capacity of a 2-D monoatomic
ideal gas in terms of the ideal gas constant R.
b) an expression for the (constant volume) heat capacity of a 2-D diatomic ideal
gas in terms of the ideal gas constant R. Assume that vibrational and rotational
degrees of freedom are energetically accessible.