Solids and Liquids PDF

LIQUIDS AND SOLIDS GENERAL CHEMISTRY 2 LEARNING OBJECTIVES At the end of the lesson, the learners should be able to; use the kinetic molecular model to explain properties of liquids and solids; describe and differentiate the types of in...

LIQUIDS AND SOLIDS GENERAL CHEMISTRY 2 LEARNING OBJECTIVES At the end of the lesson, the learners should be able to; use the kinetic molecular model to explain properties of liquids and solids; describe and differentiate the types of intermolecular forces; predict the intermolecular forces possible for a molecule; appreciate the properties of liquids; and explain the effect of intermolecular forces on these properties: surface tension, viscosity, vapor pressure, boiling point, and molar point of vaporization.  Solid Particles are tightly packed together and vibrate in place. Solids have a fixed shape and volume because the particles don't have enough kinetic energy to overcome the force of attraction between them. Liquid Particles are more spaced out than in solids, but still in contact with each other. Liquids have a fixed volume but can change shape because the particles have enough kinetic energy to slide past each other. Liquids flow because the particles are free to move and can move into openings left by other molecules.  INTERMOLECULAR FORCES OF ATTRACTION INTRAMOLECULAR FORCES -force which keeps molecule together, i.e.., bonds. INTERMOLECULAR FORCES -attractive force between molecules responsible for keeping matter in solid or liquid phase INTERMOLECULAR FORCES OF ATTRACTION A. DIPOLE-DIPOLE FORCES Forces that occur between polar molecules with permanent dipole. Polar molecule- molecule that contain dipole moment Dipole moment- two opposite and equal charge separated by a distance  INTERMOLECULAR FORCES OF ATTRACTION The polarities of more than 2 atoms in molecules on the following; A. Geometry of the molecule B. Polarities of the bond C. Arrangement of non-binding electrons NOTE: The dipole moment is a vector quantity B. LONDON FORCES Also known as dispersion force. It is responsible for the molecular bonding of non-polar liquid and solid molecules. It is due to the motion of the electrons that a distorted molecules is created thus producing a temporary dipole moment (instantaneous dipole). The induced dipole on the neighboring molecule causing an attraction. B. LONDON FORCES Named after FRITZ LONDON Dispersion means pattern of distribution Exhibited by Non-Polar molecules only Involves formation of temporary dipoles C. HYDROGEN BOND It is formed when a hydrogen atom of one molecule and a pair of unshared electrons on the electronegative atom of another molecule are mutually attracted red ball- O white ball- H Note: Hydrogen bond exist between H and elements such as O, N and F.  C. HYDROGEN BOND Hydrogen bond explains the unusual strong intermolecular force of attractions of certain hydrogen containing compound. It is also account for the unexpectedly high solubility of some compounds containing oxygen, nitrogen, and flourine in certain hydrogen containing solvent like water.  LIQUID Has no definite shape since in its motion defy the attractive forces that fix the molecules into definite positions into crystal structures. Has a definite volume since molecules moves so slowly (unlike gas that moves rapid) and this intermolecular attractive forces will hold them together into a definite volume. LIQUID PROPERTIES Viscosity- resistance to flow due to the attractions between molecules. THERMODYNAMIC- variable that affect the viscosity PROPERTIES 1. TEMPERATURE- increasing the temperature decreases the viscosity of the liquid since the cohesive forces is overrun by the increasing molecular motion. 2. PRESSURE- increasing pressure, generally increases the viscosity  WAYS OF MEASURING THE VISCOSITY 1. Using the gravity 2. Viscometer  SURFACE TENSION Another property of the liquid which causes by the strong cohesive forces between the surface molecules and their neighbor molecules below them. the result is lower energy in the interior molecules than in the exterior (or surface molecules). SURFACE TENSION  VAPOR PRESSURE It is the equilibrium vapor pressure that exist between vapor and liquid at a given temperature.  Equilibrium Vapor Pressure NOTE: The equilibrium vapor increases as temperature increases.  EVAPORATION It is a type of vaporizaton process in which energy from the sorrounding flows into the liquid causing the molecules to gain high kinetic energies and if sufficient enough will overcome the intermolecular forces causing the liquid to enter the gas phase. Evaporation is one of the two types of vaporization process. The other one is boiling  EFFECTS OF TEMPERATURE The rate of evaporation increases as the temperature increases since the average kinetic energy of the molecules increases as well as the number of molecules high enough to escape to gas phase.  BOILING POINT The temperature at which the vapor pressure of a liquid equals the external pressure. Changing the external pressure will adjust the boiling point of a liquid. Difference between boiling and evaporation  FREEZING POINT When liquid is cooled, the molecules move slowly. Eventually the temperature is reached with some molecules having a kinetic energy low enough to allow intermolecular attractions to hold them together in crystal structure.  Phase Diagram of Water This is a curve that shows the conditions under which water can exist as solids, liquid and vapor and the conditions that bring about changes in the state of water  Terminologies in Freezing Supercooled liquids- below its freezing point Freezing point- temperature at which solid and liquid are in equilibrium under atm. Melting point- temperature at which solid-liquid equilibrium is attained under 1atm when crystalline substance is heated. Molar enthalpy of fusion (ΔH)- heat that must be added to melt a mole of material. Vapor Pressure of the solid- measure the number of molecules in a given volume of the vapor at equilibrium. Vapor-solid equilibrium exist when rate of the vapor leaving the crystal is equal to the rate at which it return to the crystal.  ENTHALPHY OF VAPORIZATION The amount heat that must be supplied to vaporize a mole of a liquid at a specified temperature is known as molar enthalpy of vaporization This energy supply the liquid needed to overcome the intermolecular force of attractions and to overcome the surrounding atmosphere for vapor to expand. The opposite is known as Enthalpy of Condensation in which the value is numerically equal but opposite in sign Note: The enthalpy of vaporization is inversely proportional with temperature. Why do you think so? Clausius Clapeyron Equation Clausius Clapeyron Equation  Clausius Clapeyron Equation SAMPLE PROBLEM: The vapor pressure of a substance is 21torr at 300K. Calculate the vapor pressure at 310K if the enthalpy of vaporization is 24kJ/mol.  Clausius Clapeyron Equation SAMPLE PROBLEM: The vapor pressure of a substance is 30torr at 250K. At what temperature will the substance have a vapor pressure of 150torr? The enthalpy of vaporization is 45kJ/mol.  Clausius Clapeyron Equation SAMPLE PROBLEM: Mercury is heated from 300K to 310K, increasing its vapor pressure from 100torr to 150torr. Calculate the heat of vaporization of Mercury.  Clausius Clapeyron Equation SOLVE The vapor pressure of a substance is 70torr at 280K. Calculate the vapor pressure at 350K if the enthalpy of vaporization is 28kJ/mol.  Clausius Clapeyron Equation SOLVE The vapor pressure of a substance is 25torr at 150K. At what temperature will the substance have a vapor pressure of 100torr? The enthalpy of vaporization is 24kJ/mol.  Clausius Clapeyron Equation SOLVE Water’s vapor pressure increases from 50torr at 250K to 100torr at 260K. Determine the heat of vaporization of water. THANK YOUUUU!!