Flashcards
Chem 123 - Chapter 10
Flashcards do conjunto (95)
- 1Ionic bonds are sometimes called ion-ion forces. These are not intermolecular forces because.....Molecules are not involved.
- 2The attractive force between ions is proportional...to the charges on the ions
- 3The attractive force between ions is inversely proportional to...the distance between ions
- 4Ions will experience stronger interactions if they are (larger/smaller) and have (larger/smaller) charges.smaller, and have larger charges;j in large ions the centers are farther apart
- 5Strong forces mean a substance is (more/less) likely to be a solid and requires (more/less) energy to convert into a liquid or gas.More, more; the stronger the force, the more you have to pull so more energy is required
- 6Forces between ions are very strong forces and, traditionally all ionic compounds were thought to be solids. Within the past twenty years ionic compounds have been made with very large ions and small charges.These compounds can be liquids at room temperature and have interesting properties and utility as solvents.
- 7Ion-Dipole (positive with negative end) interactions are...are interactions between ions and polar molecules. Important in solutions (ionic solutes in polar solvents)
- 8In water, a sphere of hydration is...formed around ions (which organizes the solvent molecules). More highly charged ions have larger hydration spheres (shells).
- 9The oppositely-charged end of a dipole (polar molecule) is attracted to...an ion.
- 10IMF - Vanderwaalsdue to attractions between opposite charges (electrostatic), and are weaker than ionic and covalent bonds
- 11Intermolecular ForcesAttraction between different neutral molecules- not between each atom
- 12The molecules in liquids and solids are held together byattractive imf... energy must be put in to overcome these attractions and separate the molecules from each other (e.g. boil a liquid)
- 13Strong IMF = Weak IMF =solids, liquids
gas - 14the stronger the imf (the higher/lower) the boiling and melting pointshigher; higher boiling points means more energy is required to change state
- 153 types of IMF:Dipole-Dipole
Hydrogen Bonds
Dispersion Forces - 16Dipole-dipoleinteractions between 2 polar molecules; oppositely charged ends of the dipoles attract (+ to -)
- 17The greater the polarity the (stronger/weaker) the attractionstronger
- 18Polar molecules should boil at a (higher/lower) T than similar nonpolar molecules (molecules with same molar mass)higher-- they have extra forces (dipole/dipole)
- 19Polarnon-symmetric and have polar bonds
- 20Non-polarsymmetric, not a dipole
- 21Hydrogen bondsstrong imf, not really a bond because it is a imf-- special type of dipole interaction where a hydrogen atom is shared between two very electronegative atoms (N, O, or F)
- 22To Hydrogen bond one molecule must contain an (N, O, or F)-H Bond, and other molecule must contain (N, O, or F)Has a very electronegative partial charge, as molecules get bigger, Boiling Pt. gets higher
- 23Example of H bondN-H-------X-R
X = N O or F
R= Radical, doesn't matter - 24Dispersion Forcespresent in ALL molecules, polar and nonpolar; temporary (instantaneously-induced) dipoles attract
- 25As electrons moves they randomly create instantaneous dipoles which induce...dipoles in neighboring molecules...
- 26Strength of the dispersion forces depends on their ability tobe polarized
- 27Polarizability...the ease with which a molecule may be polarized
- 28In larger atoms the e- are (farther from, closer to) the nucleus; they are held (more/less) tightly; they are (harder/easier) to move around; they are (harder/easier) to polarize. This result is similar for molecules.farther from, less, easier, easier
- 29More electrons means larger molar mass which means higher polarizability. It is (harder/easier) to polarize long (elongated) molecules than spherical molecules since they have a larger surface area.Easier
- 30Strong dispersion forces when molecules are the (same/different) size.same
- 31As molar mass increases, boiling point (increases/decreases).increases
- 32Dispersion forces can be stronger or weaker than dipole-dipole or even H bonding. I2 dispersion force (>/<) H2O>
- 33The attraction between molecules are much (stronger/weaker) than the bonds within a molecule. It is easier to separate molecules from each other than to decompose a molecule.weaker
- 34All molecules experience dispersion forces. Higher MM means...Stronger attractions
- 35If a molecule is polar it will also experience dipole-dipole forces; stronger/weaker attractions than non-polar molecules of similar mmStronger
- 36If X-H bonds are present in the molecule, where X = N, O, or F, then H-bonds are also present between molecules which means (stronger/weaker) attractions.Stronger
- 37Stronger attractions mean (higher/lower) BP and melting pointsHigher
- 38Solutionhomogeneous mixture composed of solute and solvent
- 39solventwhat solute gets dissolved in
- 40solutewhat gets dissolved, can have more than one (may or may not change phase)
- 41If both components are in the same phase, the (solvent/solute) is the one present in greater quantitysolvent (does not change phase)
- 42solvationsurrounding of solute particles by solvent molecules; if the solvent is water it is called hydration
- 43When dissolved, ionic compounds (do/do not ) separate into ionsdo
- 44When dissolved, molecular (covalent) compounds (do/do not) separate into ions.do not
- 45breaking solute-solute attractive forces (requires/releases) energyrequires
- 46breaking solvent-solute attractive forces (requires/releases) energyrequires
- 47forming solute-solvent attractive forces (requires/releases) energyreleases, is going to be more stable
- 48Stronger solute-solvent attractions have (higher/lower) solubilityhigher (if they like each other they will mix)
- 49substances with similar IMF tend to be (soluble/nonsoluble) in one another. "Like dissolves like"soluble
- 50Polar soluble in (polar/nonpolar)Polar
- 51Nonpolar soluble in (polar/nonpolar)Nonpolar
- 52Ionic soluble in (polar/nonpolar) if at allpolar
- 53miscible liquidsliquids that mix in all proportions
- 54Immiscible liquidsliquids that don't mix
- 55Partially miscible liquidsliquids that mix somewhat
- 56molecules have polar heads and nonpolar tails; heads are soluble in water, tails are not. As the length of the tail grows, the molecules become (less/more) soluble in water.Less
- 57Hydrophillic "water loving"soluble in water, polar heads
- 58hydrophobic "water hating"insoluble in water, nonpolar tails
- 59Vaporization/EvaporationThrough random motion and collision, liquid molecules may obtain enough energy to escape into the vapor phase
- 60CondensationGas molecules collide with the liquid surface and are trapped
- 61Equilibriumrates of two opposing processes are equal; a larger surface area allows equilibrium to be reached more quickly
- 62Vapor pressureequals the pressure exerted by the gas when it is in equilibrium with its liquid form
- 63Weak attractive forces have (high/low) rate of vaporization and (high/low) vapor pressurehigh, high
- 64As T increases, the rate of vaporization (increases/decreases) and vapor pressure (increases/decreases)increases, increases
- 65Boiling occurs when the vapor pressure equalsthe external pressure
- 66If external pressure (pex) is greater than 1 atm the boiling point is (greater/less than) the normal boiling pt.greater, requires greater force
- 67If external pressure (pex) is less than 1 atm the boiling point is (greater/less than) the normal boiling pt.less than
- 68volatileevaporates readily or has high vapor pressure
- 69The vapor pressure of dichloromethane is 400 torr at 24.1 degrees C and 600 torr at 34.8 degrees C. What is its enthalpy of vaporization using the Clausius-Clapeyron equation?28.8 KJ/mol
- 70Energy is required to break the attractive forces between molecules, changing T can/cannot change the phasecan
- 71For a liquid or a solid to vaporize it must overcome the opposing external pressure- changing P can/cannot change the phasecan
- 72high P, low T - the most stabel phase issolid
- 73low P, high T, most stable phase isgas
- 74triple pointthe 3 phases at equilibrium
- 75line2 phases in equilibrium- phase transitions
- 76sublimationsolid to gas
- 77critical pointwhere liquid/gas line stops
- 78above critical pointsupercritical fluid (gas or liquid)
- 79At T > Tc condensation will no longer occur.The fluid will expand to occupy the volume of the container.
- 80The critical pressure, Pc, is the pressure needed toliquefy a gas at its Tc (less commonly used)
- 81At high P and T > Tc, the "gas" will have a density close to that of a liquid so it is usually referred to as...supercritical fluid (gas or liquid)
- 82Supercritical fluids have special abilities as solvents since they have excellent mass transport properties. They have much (higher/lower) viscosities and much (higher /lower) diffusion coefficients.They have much lower viscosities and much higher diffusion coefficients.
- 83Surface tensionthe energy per unit area required to increase the surface area of a liquid
- 84surface tensiongo from bulk (middle of beaker) to surface, energy increases as you move up
- 85Molecules in bulk liquid experience (more/less) attractive forces, a liquid (maximizes/minimizes) its surface area.more, minimizes
- 86energy is required to break the attractive forces and move a molecule to the surface... strong imf equals a (high/low) surface tensionhigh, more energy required
- 87cohesive forceattractive force between like molecules
- 88adhesive forceattractive force between unlike molecules
- 891. Adhesion of h20 to glass capillary pulls water up the size and forms meniscus 2. Surface tension acts to minimize the surface area and pulls up the water in the middle of the tube. 3. 1/2 repeat until force of gravity equals surface tensionMeniscus shape depends upon the relative strength of the adhesive vs. the cohesive forces present.
- 90ViscosityThe resistance of a fluid to flow
- 91Higher viscosity means (higher/lower) resistance, which means (slower/faster) flowhigher, slower
- 92Strong IMF = higher/lower viscosityhigher
- 93For nonpolar liquids such as hydrocarbons this means compounds with larger molar masses have (higher/lower) viscosity (e.g. lubricating oil vs. gasoline)higher; higher MM, higher dispersion forces, higher resistance to flow
- 94Increasing the temperatures equals a (higher/lower) viscositylower, more energy easier to move
- 95HalogensGroup 17
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- Chem 123 FlashCards sobre Chem 123 - Chapter 10, criado por Hannah Tobiczyk em 26-01-2015.
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- Hannah Tobiczyk
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