The solute, A, has broken from the intermolecular forces holding it together and the solvent, B, has broken from the intermolecular forces holding it together as well. It is at this time that the third process happens. We also have two values and Both of these values are greater than zero (again, because both ΔH1 ΔH2. processes are endothermic) The third process is when substance A and substance B mix. The separated solute molecules and the separated solvent molecules join together to form a solution. This solution will contain one mole of the solute A in an infinite amount of the solvent B. The enthalpy of combining these two substances to form the solution is called ΔH3. This is an exothermic reaction, because energy is given off as the two substances bond together; therefore, < 0. ΔH3 The final value for the enthalpy of solution can either be endothermic or exothermic (so ΔHsolution can either be greater than zero or less than zero), depending on how much energy is required or given off in each step. The enthalpy of solution can be written as a formula; = + + ΔHsolution ΔH1 ΔH2 ΔH3. If = 0, then solutions are called ideal solutions. ΔHsolution If > 0 or < 0, then these solutions are called non-ideal solutions. ΔHsolution ΔHsolution The enthalpy of solution depends on the intermolecular forces of the solute and solvent. If the solution is ideal, and = 0, then that means added to is equal to ΔHsolution ΔH1 ΔH2 ΔH3. This means the forces of attraction between like (the solute-solute and the solvent-solvent) and unlike (solute-solvent) molecules are the same. If the solution is then either added to is greater than or is greater than the ΔH1 ΔH2 ΔH3 ΔH3 sum of and ΔH1 ΔH2. The first case means the forces of attraction of unlike molecules is greater than the forces of attraction between like molecules.
The solute, A, has broken from the intermolecular forces holding it together and the solvent, B, has broken from the intermolecular forces holding it together as well. It is at this time that the third process happens. We also have two values ΔH1 and ΔH2. Both of these values are greater than zero (again, because both processes are endothermic) The third process is when substance A and substance B mix. The separated solute molecules and the separated solvent molecules join together to form a solution. This solution will contain one mole of the solute A in an infinite amount of the solvent B. The enthalpy of combining these two substances to form the solution is called ΔH3. This is an exothermic reaction, because energy is given off as the two substances bond together; therefore, ΔH3 < 0. The final value for the enthalpy of solution can either be endothermic or exothermic (so ΔHsolution can either be greater than zero or less than zero), depending on how much energy is required or given off in each step. The enthalpy of solution can be written as a formula; ΔHsolution = ΔH1 + ΔH2 + ΔH3. If ΔHsolution = 0, then solutions are called ideal solutions. If ΔHsolution > 0 or ΔHsolution < 0, then these solutions are called non-ideal solutions. The enthalpy of solution depends on the intermolecular forces of the solute and solvent. If the solution is ideal, and ΔHsolution = 0, then that means ΔH1 added to ΔH2 is equal to ΔH3. This means the forces of attraction between like (the solute-solute and the solvent-solvent) and unlike (solute-solvent) molecules are the same. If the solution is then either ΔH1 added to ΔH2 is greater than ΔH3 or ΔH3 is greater than the sum of ΔH1 and ΔH2. The first case means the forces of attraction of unlike molecules is greater than the forces of attraction between like molecules.