New version page

NIU CHEM 211 - Exam 1 Study Guide

Type: Study Guide
Pages: 10
Documents in this Course
Load more

This preview shows page 1-2-3 out of 10 pages.

View Full Document
View Full Document

End of preview. Want to read all 10 pages?

Upload your study docs or become a GradeBuddy member to access this document.

View Full Document
Unformatted text preview:

CHEM 211 1st Edition Exam # 1 Study Guide Chapters: 1-10I. Phases of MatterA. Each physical state of matter is a phase, a physically distinct, homogeneous part of a system.B. The potential energy, in the form of attractive forces, tends to draw particles together.C. The kinetic energy associated with movement tends to disperse particles.II. Attractive ForcesA. Intramolecular forces = bonding forces. (Influence the chemical properties)a) These forces exist within each molecule.B. Intermolecular forces = nonbonding forces. (Influence the physical properties)b) These forces exist between molecules.III. Kinetic Molecular View of the Three States>IV. Phase ChangesC. Sublimation is from the solid phase to the gasphase without passing through anintermediate liquid phase.D. Vaporization is substance from the liquid phase to the gas phase.E. Condensation is from the gas phase to liquid phase.F. Deposition is a process where a gas changes phase and turns directly in solid without passing through the liquid phase.G. Freezing is almost always an exothermic process, meaning that as liquid changes into solid, heat and pressure is released.H. Melting changes from the solid phase to the liquid phase.V. Quantitative Aspects of Phase ChangesA. Within a phase, heat flow is accompanied by a change in temperaturec) q = n x C x ∆TB. During a phase change the average distance between particles changes.d) q = n x ∆HVI. Liquid-gas equilibriumC. In a closed flask, the system reaches a state of dynamic equilibrium, where molecules are leaving and entering the liquid at the same rate.D. If you add more solvent, it will still be the same because it is still at equilibrium.VII. Factors affecting Vapor PressureE. Vapor pressure is the pressure exerted by the vapor on the liquid. The pressure increases until equilibrium is reached; at equilibrium the pressure is constant.F. As temperature increases, the fraction of molecules with enough energy to enter the vapor phase increases, and the vapor pressure increases.e) Higher T > higher P.G. The weaker the intermolecular forces, the more easily particles enter the vapor phase, and the higher the vapor pressure.f) Weaker forces > higher P.H. Vapor pressure increases as temperatureincreases.I. Vapor pressure decreases as the strength of the intermolecular forces increases.VIII. The Clausius - Clapeyron EquationA. Relates vapor pressure to temperature.B. Used when the vapor pressures at two different temperatures are known.IX. Vapor Pressure and Boiling PointA. The boiling point of a liquid is the temperature at whichthe vapor pressure equals the external pressure.B. At 760 torr.C. As the external pressure on a liquid increases, the boilingpoint increases.X. Phase diagram for CO2 and H2OA. At the critical point, the densities of the liquid and gasphases become equal.B. At the triple point, all three phases are in equilibrium.C. The solid-liquid line slants to the left for H2O, because the solid is less dense than the liquid. Water expands on freezing.XI. The Nature of Intermolecular ForcesA. Intermolecular forces are relatively weak compared to bonding forces because they involve smaller charges that are farther apart.XII. Covalent and Van der Waals radiiB. The van der Waals distance is the distance between two non-bonded atoms in adjacent molecules.C. The van der Waals radius is one-half theclosest distance between the nuclei of twonon-bonded atoms. D. The VDW radius is always larger than thecovalent radius.E. Increases down a group and increases rightto left.XIII. Comparison of Bonding and Nonbonding(Intermolecular) ForcesXIV. Polar molecules, dipole-dipole forces,dipole momentA. The positive pole of one polar molecule attracts the negative pole of another.B. Solid is in a pattern while liquid is more randomly placedXV. The Hydrogen BondA. Hydrogen bonding is possible for molecules that have a hydrogen atom covalently bonded to a small, highly electronegative atom with lone electron pairs, specifically N, O,or F.B. An intermolecular hydrogen bond is the attraction between the H atom of one molecule and a lone pair of the N, O, or F atom of another molecule.XVI. Polarizability and Induced DipolesA. A nearby electric field can induce a distortion in the electron cloud of an atom, ion, or molecule.B. For a nonpolar molecule, this induces a temporary dipole moment.C. For a polar molecule, the field enhances the existing dipole moment.D. The polarizability of a particle is the ease with which its electron cloud is distorted.E. Smaller particles are less polarizable than larger ones because their electrons are held more tightly.F. Polarizability increases down a group because atomic size increases and larger electron clouds distort more easily.G. Polarizability decreases across a period because of increasing Zeff (effective nuclear charge).H. Cations are smaller than their parent atoms and less polarizable; anions show the opposite trend.I. Polarizability correlates closely with molar mass for similar particles.XVII. Dispersion (London) ForcesA. Dispersion forces exist between all particles, increasing the energy of attraction in all matter.B. Dispersion forces are stronger for more polarizable particles. C. In general, larger particles experience stronger dispersion forces than smaller ones.D. When atoms are far apart they do not influence one other.E. When atoms are close together, the instantaneous dipole in one atom induces a dipole in the other.XVIII. Molecular shapeA. In a more rectangular molecule there are more points at which dispersion forces act.B. In a rounder molecule there are fewer points at which dispersion forces act.XIX. Surface TensionA. A surface molecule experiences a net attraction downward. This causes a liquid surface to have the smallest area possible.B. An interior molecule is attracted by others on all sides.C. Surface tension is the energy required to increase the surface area of a liquid. The stronger the forces between the particles the higher the surface tension.XX. CapillarityA. High capillarity = water rises through the tiny spaces between soil particles, so plant roots can absorb deep groundwater during dry periods.B. Water = concave meniscus.C. Mercury = convex meniscus.XXI. ViscosityA. Viscosity is resistance to flow.B. Results from intermolecular attractions that impede the movement of molecules aroundand past each other.C. Both gases and


View Full Document
Loading Unlocking...
Login

Join to view Exam 1 Study Guide and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Exam 1 Study Guide and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?