Investigating Intermolecular Forces

INVESTIGATING INTERMOLECULAR FORCES WHAT ARE INTERMOLECULAR FORCES? 01 Intermolecular forces are the attractive forces between molecules that hold the particles together in the condensed states of matter (solid or liquid). They determine the physical properties of the molecule such as boiling point, melting point and viscosities. THE INTERMOLECULAR FORCES AND THE 02 COSMETICS INDUSTRY van der Waals forces London- dispersion forces (LDF) LDF's are the weakest of the intermolecular forces and are present within all polar and non-polar molecules.They play an important role in the cosmetics industry, especially in the production of non-polar products like oils, waxes, and different kinds of makeup. LDF occur when temporary shifts in electron density create temporary dipoles that attract neighboring molecules. In cosmetics, these forces help hold together the molecules in products like lipsticks, creams, and foundations, particularly those made with hydrocarbons or long-chain fatty acids Hydrogen bonding H-bonding is the strongest van der Waal attraction. Hydrogen bonding is a strong type of intermolecular force that occurs when hydrogen is covalently bonded to a highly electronegative atom for example, nitrogen, oxygen, or fluorine and is attracted to the lone pairs of another nearby N, O, or F atom in a different molecule. In the cosmetics industry, hydrogen bonding is used or product absorption and texture, especially in water-based products. Ingredients such as hyaluronic acid, and proteins form hydrogen bonds with water molecules, help retain moisture and improve skin hydration. These bond also contibute to the thickness of gels, creams, and emulsions. For example, moisturizers keep the skin soft and hydrated due to the hydrogen bonding between water and glycerin, which helps hold water in the product and on the skin. Dipole- dipole interactions Dipole-dipole atractionsccur between polar molecules with a permanent dipole where the center of the positive charge of one molecule is attracted to the center of the negative charge of another molecule. In the cosmetics industry, dipole-dipole forces play an important role in the formulation of water-based products like lotions, serums, and creams. Ingredients such as glycerin, niacinamide, and alcohols rely on these interactions to dissolve properly in polar solvents like water and to maintain even distribution throughout a product. These forces also contribute to the smooth texture, especially in emulsions where both water- and oil-soluble ingredients must remain blended. SOLUBILITY OF ORGANIC COMPOUNDS+ 03 SOLUBILITY IN WATER The solubility of organic compounds and how well a compound dissolves in a solvent, is determined by the IMFs . Polar organic compounds dissolve in polar solvents due to hydrogen bonding or dipole-dipole forces. Non-polar compounds dissolve in non-polar solvents due to London dispersion forces. This can remembered by "Like dissolves like": polar with polar, non-polar with non-polar. Water is a polar molecule that forms strong hydrogen bonds, so it dissolves other polar substances and ionic compounds due to sttractions like hydrogen bonding and ion-dipole forces. For example, salt (NaCl) dissolves because its positive and negative ions are attracted to the partial charges on water molecules. Nonpolar substances like oils do not dissolve in water because they only posses weak LDFs and cannot interact effectively with water’s polar molecule. This is why water and oil do not mix because of incompatible IMFs. MELTING AND BOILING POINTS OF SUBSTANCES The stronger the IMFs between molecules, the more energy (heat) is required to overcome those forces and change states of matter from solid to liquid (melting) or from liquid to gas ( boiling) Hydrogen bonding > Dipole-dipole interactions > LDF's is the order of strongest IMF's to weakest. Therefore a substance with H-bonding will have a higher melting and boiling point than a compound with only LDF and dipole dipole. 04 THE CREATION OF OIL & VINEGAR SALAD THE STATE OF LIPIDS AT DRESSINGS AND PARTIALLY 04 ROOM TEMPERATURE The state of lipids at room temperature is determined by the type of IMFs between their molecules, depending on the structure of the fatty acids they contain. Saturated fats have straight hydrocarbon chains that pack closely together, leading to stronger London dispersion forces .This tight packing and creates stronger IMFs, saturated fats are usually solid at room temperature, for example, butter or lard Unsaturated fats contain one or more double bonds in their hydrocarbon chains. These double bonds causing bends in the chains, preventing tight packing. As a result, IMFs are weaker, and the lipids are usually liquid at room temperature for example, olive oil. 05 HYDROGENATED VEGETABLE OIL The creation of foods like oil and vinegar salad dressings and partially hydrogenated vegetable oil demonstatrate how IMFs influence solubility and physical properties in food. Oil is nonpolar and vinegar is polar containing water and acetic acid therefore do not mix. Oil relies on LDF, while vinegar uses h- bonding and dipole-dipole interactions. This leads to separation unless an emulsifier is added to bridge the polar and nonpolar components. Partially hydrogenated vegetable oils, unsaturated fats are chemically modified by adding hydrogen atoms, straightening the chains and increasing London dispersion forces, allowing the molecules to condense, turning the oil into a more solid or semi-solid lipid at room temperature. Sources Organic Chemistry report: Boiling points of compounds. Organic Chemistry Report: Boiling Points of Compounds. (n.d.). https://desklib.com/study-documents/organic-chemistryboiling-points/ Intermolecular Forces 1.8 assignment (PDF). (n.d.-d). https://www.cliffsnotes.com/study-notes/22159746 Chapter 12 intermolecular forces and the physical ... (n.d.-c). https://www1.udel.edu/chem/sametz/101Fall09/ch12temp.pd Luella. (2014a, October 2). Intermolecular Forces. SlideServe. h https://www.slideserve.com/luella/intermolecular-force