Saltwater
Vinegar
Apple juice
Water
I’m glad you asked me about the forces between particles of different substances and water. This is a very interesting topic that involves the concepts of intermolecular forces, polarity, and solubility. Let me explain it to you in detail.
Intermolecular forces (IMFs) are the attractive forces between the particles of a substance, such as atoms, molecules, or ions. IMFs are weaker than the intramolecular forces that hold the particles together, but they are still important for determining many physical properties of substances, such as their phase, melting point, boiling point, solubility, and viscosity.
There are three main types of IMFs: dispersion forces, dipole-dipole attractions, and hydrogen bonding. Dispersion forces are the weakest type of IMFs and they occur between all particles, regardless of their polarity. They are caused by the temporary fluctuations in the electron clouds of the particles, which create temporary dipoles that attract each other. Dipole-dipole attractions are stronger than dispersion forces and they occur between polar molecules, which have permanent dipoles due to the unequal sharing of electrons between atoms with different electronegativities. Hydrogen bonding is a special type of dipole-dipole attraction that occurs when a hydrogen atom is covalently bonded to a highly electronegative atom, such as fluorine, oxygen, or nitrogen, and is attracted to another electronegative atom on a neighboring molecule. Hydrogen bonding is the strongest type of IMFs and it is responsible for many of the unique properties of water.
Water is a polar molecule that has a bent shape and a partial negative charge on the oxygen atom and a partial positive charge on the hydrogen atoms. Water molecules can form hydrogen bonds with each other and with other polar molecules that have electronegative atoms. Water can also form dispersion forces with nonpolar molecules, but these are much weaker than hydrogen bonds.
The strength of the IMFs between water and another substance determines how well that substance can dissolve in water or mix with water. Solubility is the ability of a substance to dissolve in a solvent, such as water. Solubility depends on several factors, such as temperature, pressure, and the nature of the solute and solvent. A general rule of thumb is that “like dissolves like”, which means that substances with similar polarity and IMFs tend to be more soluble in each other than substances with different polarity and IMFs.
Vinegar is a solution of acetic acid (CH3COOH) and water. Acetic acid is a polar molecule that has an O-H bond and a C=O bond, which create partial negative charges on the oxygen atoms and partial positive charges on the hydrogen and carbon atoms. Acetic acid molecules can form hydrogen bonds with water molecules and with each other, as well as dispersion forces. Therefore, vinegar has strong IMFs with water and is very soluble in water.
Apple juice is a mixture of water, sugars, organic acids, and other compounds. Sugars are polar molecules that have multiple O-H bonds and C=O bonds, which create partial negative charges on the oxygen atoms and partial positive charges on the hydrogen and carbon atoms. Sugars can form hydrogen bonds with water molecules and with each other, as well as dispersion forces. Organic acids are similar to acetic acid in their polarity and IMFs. Therefore, apple juice has strong IMFs with water and is very soluble in water.
Saltwater is a solution of sodium chloride (NaCl) and water. Sodium chloride is an ionic compound that consists of positively charged sodium ions (Na+) and negatively charged chloride ions (Cl-). When sodium chloride dissolves in water, the ions separate from each other and become surrounded by water molecules. The water molecules orient themselves such that their partial negative charges on the oxygen atoms face the sodium ions, and their partial positive charges on the hydrogen atoms face the chloride ions. This creates an electrostatic attraction between the ions and the water molecules called ion-dipole attraction, which is stronger than hydrogen bonding. Therefore, salt water has very strong IMFs with water and is highly soluble in water.
Water is a pure substance that consists only of water molecules. Water molecules can form hydrogen bonds with each other and dispersion forces. Therefore, water has moderate IMFs itself.