So I am trying to understand in molecular terms the solubility of NaCl in water.
So there are intramolecular forces that are mostly ionic between the ions, creating this partial positive, partial negative substance. And the intermolecular forces are also ionic. Ionic forces are the strongest of the intermolecular forces, right?
So if this is the case, why does NaCl dissolve in water because the hydrogen bonds shouldn't be strong enough to break the ionic bonds. Is it because there are so many hydrogen bonds that they end up breaking the single ionic bond?
Thanks!
take a look at charge - dipole attraction
http://www.chem.ufl.edu/~itl/4411/lectures/lec_g.html
One major correction. It is true that the intermolecular forces (the water molecules pulling at the lattice energy) but those are ion-dipole forces and not ionic. Charged yes but not ionic).
The answer to your question is that youmust take into account the energy gained when the Na^+ and Cl^- are broken away from each other then they can form the hydrated ions, Na^+(aq) and Cl^-(aq). Those formations are exothermic while the forces to break the lattice bonds in the crystal are endothermic. The extra oomph NaCl needs to dissolve comes from those hydrated ions.
I'm still a little bit unsure. The website didn't really specify why the ions disassociate with each other and associate with hydrogen bonding
Ok, I think I get it. Thank you both very much!
Look at it this way. The dipoles from the H2O molecules attract the Na^+ and Cl^- and pull on them. That's the pull to disrupt the crystal lattice energy. And it isn't a one step here to disrupt the crystal lattice and then another step to form the hydrates. It's the total energy of the disruption of the lattice energy + the energy gained by the formation of the hydrates and that total is positive so the "reaction" can take place.
To understand the solubility of NaCl in water in molecular terms, let's break it down step by step:
1. Intramolecular Forces: In NaCl, the sodium (Na) and chloride (Cl) ions are held together by ionic bonds, which are a type of intramolecular force. These bonds are formed due to the electrostatic attraction between the positively charged sodium ion and the negatively charged chloride ion.
2. Intermolecular Forces: When NaCl dissolves in water, the ionic crystal structure of NaCl is broken apart and the ions become surrounded by water molecules. The interaction between the ions and the water molecules involves intermolecular forces.
3. Ionic Interactions with Water: Water is a polar molecule, meaning it has a partial positive charge on the hydrogen atom and a partial negative charge on the oxygen atom. When NaCl is added to water, the partial positive charge of the water molecules (on the hydrogen atoms) is attracted to the chloride ions (negative) while the partial negative charge (on the oxygen atoms) is attracted to the sodium ions (positive). This results in the dissociation of NaCl into individual sodium and chloride ions in water.
4. Ion-Dipole Interactions: The interaction between the ions and water molecules is called an ion-dipole interaction, which is a type of intermolecular force. The strength of these ion-dipole interactions is similar in magnitude to the strength of ionic bonds, but they are not strong enough to break the ionic bonds completely.
5. Hydration: Each ion in the NaCl crystal is typically surrounded by a shell of water molecules. This process is called hydration. The partially negative oxygen atoms of water form hydrogen bonds with the sodium ions (due to the oxygen's lone pairs) and the partially positive hydrogen atoms of water form hydrogen bonds with the chloride ions. These hydration shells help stabilize the individual ions in solution by reducing the attraction between neighboring ions.
6. Solubility: The solubility of NaCl in water is a balance between the energy required to break the ionic bonds and the energy released when new ion-dipole interactions and hydration shells are formed. In the case of NaCl, the energy released by ion-dipole interactions and hydration exceeds the energy required to break the crystal lattice, resulting in the solubility of NaCl in water.
In summary, NaCl dissolves in water because of the strong attractions between the polar water molecules and the charged Na+ and Cl- ions. These attractions, along with the formation of hydration shells, help overcome the energy required to break the ionic bonds in NaCl and thus allow for its dissolution in water.