Final answer:
The average translational kinetic energy of an oxygen molecule at STP is approximately 6.02 x 10^-21 J. The total translational kinetic energy of 2.0 mol of O2 molecules at 20°C depends on the temperature given in the question. The rms speed of helium atoms near the surface of the sun at a temperature of about 6000 K depends on the temperature and the molar mass of helium.
Step-by-step explanation:
The average translational kinetic energy of an oxygen molecule at standard temperature and pressure (STP) can be calculated using the formula KE = (3/2) kT, where KE is the average kinetic energy, k is Boltzmann's constant (1.38 x 10^-23 J/K), and T is the temperature in Kelvin. At STP, the temperature is 273.15 K. Plugging in these values, we get KE = (3/2) × (1.38 x 10^-23 J/K) * 273.15 K = 6.02 x 10^-21 J.
For part (b), to find the total translational kinetic energy of 2.0 mol of O2 molecules at 20°C, we first convert the temperature to Kelvin by adding 273.15 to it. Then, we use the formula KE = (3/2) kT to calculate the kinetic energy per molecule and multiply it by Avogadro's number (6.022 x 10^23 mol^-1) and the number of moles (2.0) to get the total kinetic energy. The final result depends on the temperature given in the question.
For part (c), to calculate the root-mean-square (rms) speed of helium atoms near the surface of the sun at a temperature of about 6000 K, we use the formula v = sqrt(3kT/m), where v is the rms speed, k is Boltzmann's constant, T is the temperature in Kelvin, and m is the mass of the molecule. Given the temperature and the molar mass of helium (4.003 g/mol or 0.004003 kg/mol), we can calculate the rms speed. The result depends on the temperature given in the question.