Two volatile liquids "A" and "B" form a solution whose mole fraction vs. vapor pressure sketch (at 25 ◦ C ) is show below. An equimolar mixture of liquids A and B are placed in a closed container (at 25 ◦ C ). At equilibrium, the vapor above the mixture will be

Heat is involved in chemical change in two ways; chemical changes either result in heat being added to or removed from an object, and chemical changes require a certain amount of heat before they can take place.

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.