Medical Chemistry Lecture Notes PDF

Medical Chemistry Almaaqal University Collage of Dentistry Solutions and colloidal system Dr/ Wael Sobhy Darwish Lec-5 1ST stage&2024  Sol...

Medical Chemistry Almaaqal University Collage of Dentistry Solutions and colloidal system Dr/ Wael Sobhy Darwish Lec-5 1ST stage&2024  Solutions and colloidal system Fluids in living system are complex mixture of colloids, ions and molecules. The behavior of these fluids in the body is vital of life. A solution is a mixture of two or more components. 1- The solute is the substance that is being dissolved to form a solutions. 2- The solvent is the dissolving medium A solution is a homogeneous mixture consisting of a solute dissolved into a solvent.  Component of Solution  Solutions Heterogeneous Homogeneous Heterogeneous: mixture are Homogeneous: mixture are those which are not those in which the smallest homogenous samples are everywhere identical in composition and properties. Types of binary solutions  Factors Affecting Solubility: The solubility of a substance depends on the physical and chemical properties of that substance. In addition to this, there are few conditions which can manipulate it. 1. Temperature 2. Pressure. 3. The type of bond and forces between the particles( Intermolecular forces ) Types of Solutions  Types of Solutions 1. An unsaturated solution is a solution in which a solvent is capable of dissolving any more solute at a given temperature. 2. Saturated solutions - A solution in which no more solute can be dissolved at a given temperature is called as saturated solution. 3. Supersaturated: It contains more solute than the maximum amount of solute that will dissolve in the solvent. This is typically created by saturating a solution at a higher temperature and then slowly cooling it to a lower temperature. Supersaturated Solution  Colloids and colloidal dispersions Colloids are mixtures of two or more substances where one substance is dispersed within another. The dispersed substance is referred to as the “dispersed phase”. The medium in which it is dispersed is known as the “dispersion medium”.  Colloids and colloidal dispersions A colloidal solution typically consists of particles ranging in size from 1 nanometer to 1 micrometer. These particles can be solid, liquid, or gas. Unlike true solutions where solute particles are dissolved at a molecular level, colloidal particles remain suspended in the dispersion medium without settling down due to gravity, thus forming a heterogeneous mixture.  Properties of colloids It is a heterogeneous mixture. The size of colloidal particles is very small. It shows the Tyndall effect. They don't settle down when left undisturbed for some time. They cannot be separated by the filtration process. They can be separated by centrifugation.  Tyndall effect when a strong beam of light is focused on a colloidal solution the path of the beam becomes visible. This phenomenon is known as Tyndall effect.  Types of colloids Based on the nature of the interaction between the dispersion medium and the dispersed phase, colloids can be classified into lyophilic and lyophobic. 1- Lyophilic If the dispersed phase has an affinity for the dispersion medium, the colloid is called a lyophilic colloid. The words lyo and philic mean ‘liquid’ and ‘loving’ respectively. Thus, even if the dispersed phase is separated from the dispersion medium, they can readily be reconstituted by simply mixing them. Moreover, they are difficult to coagulate due to their stable nature. They are also known as intrinsic colloids. Examples are starch, rubber, protein, etc.  2 Lyophobic If the dispersed phase has little or no affinity for the dispersion medium, the colloid is called a lyophobic colloid. The words lyo and phobic mean ‘liquid’ and ‘fearing’ respectively. Hence, they are liquid-hating. They are difficult to prepare because the dispersed phase does not readily form a colloid with the dispersion medium; they require some special methods. They are unstable and require stabilising agents for their preservation. They are also known as extrinsic colloids. Examples are solutions of metals like silver and gold.  Applications of Colloid 1. A colloid is used as thickening agents in industrial products such as lubricants, lotions, toothpaste, coatings. 2. In the manufacture of paints and inks, colloids are useful. 3. In food and Beverage Industry for stabilization, texture enhancement, and emulsification in food and beverage production. 4. Colloidal systems are essential in nanotechnology applications 5. In dentistry, various colloidal systems are used in dental materials 6. Colloidal systems have a potential role in drug delivery systems in dentistry  Suspensions A suspension is a heterogeneous mixture containing solid particles with a diameter greater than 1000 nm that are sufficiently large for sedimentation. The particles are visible to naked eyes. In this type of mixture, all the components are completely mixed and all the particles can be seen under a microscope. Ex: Muddy water  Properties of Suspension A suspension is a heterogeneous mixture. The size of solute particles in a suspension is quite large. The particles of a suspension can be seen easily. The particles of a suspension do not pass through a filter paper. So a suspension can be separated by filtration. The suspension is unstable. The particles of a suspension settle down after some time. A suspension scatters a beam of light passing through it because of its large particle size. 1 to 1000 nm More than 1000 nm