Question

Calculate the kinetic energy of CO at 274 K. Express the answer as E_avg = in joules per mole to three significant figures.

Calculate the kinetic energy of CO₂ at 274 K. Express the answer E_avg = joules per mole to three significant figures.

Calculate the kinetic energy of SO₃ at 274 K. Express teh answer E_avg = joules per mole to three significant figures.

Answer 1

For gas molecules kinetic energy does not depend on mass of the molecule/s and is given by,

E_avg = (3/2)*nRT

where, n is number of moles of gas, R = ideal gas constant = 8.314 JK^-1mol^-1; T is absolute temperature.

Given, T = 274 K; so for one mole of any gas,

E_avg = (3/2)*RT = (3/2) * 8.314 * 274 = 3417.05 Jmol^-1

Hence, average kinetic energy for any gas (CO or CO₂ or SO₃ or any other gas) at 274 K

is 3417.05 Jmol^-1​. Since, answer is to be expressed with three significant figures, it can be approximated as,

3420 Jmol^-1.

Answer: Kinetic energy for any gas (CO or CO₂ or SO₃ or any other gas) at 274 K

is, E_avg = 3420 Jmol^-1 = 3.42 kJmol^-1​.                     (1000 J = 1kJ)