At 400.0 K, an equilibrium mixture of H2, I2, and HI consists of 0.0650 mol H2, 0.0790 mol I2, and 0.130 mol HI in a 4.50-L flask. What is the free energy of this reaction?

The molecules contain like 54 of water 

Oxygen= 88ghydrogen= 12g

Vander waals forces are inter molecular bonds that exist within molecules of the same substance. a water molecule is made up of oxygen and hydrogen atoms which share electrons between each other. the vander waals forces are forces that exist between multitude of different  molecules of water. dipole dipole forces is the type of vander waals force that exist in water. the oxygen atom which is more electronegative pulls the shared electron closer to itself thus generating a partial negative charge while the hydrogen acquire a partial positive charge. these two different charges causes attraction to occur in water molecules.