Calculate the energy e of a sample of 3.50 mol of ideal oxygen gas (o2) molecules at a temperature of 310 k. assume that the molecules are free to rotate and move in three dimensions, but ignore vibrations.

13.53 kJ

Explanation:

The energy of a gas can be calculated by the equation:

E = (3/2)*n*R*T

Where n is the number of moles, R is the gas constant (8.314 J/mol.K), and T is the temperature.

E = (3/2)*3.5*8.314*310

E = 13,531.035 J

E = 13.53 kJ

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.