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75 Cards in this Set
- Front
- Back
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what does VSEPR stand for?
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Valance-shell electron-pair repulsion
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what is VSEPR
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electon pairs in a valence shell strive to get as far away as possible from all other electron pairs in the shell
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# of faces on a tetrahedron?
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4
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substituent
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an atom or nonbonding pair of electrons surrounding a central atom
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# of substituents oxygen atom in H2O has
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4; 2 H atoms & 2 non-bonding pairs of electrons
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dipole
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a separaation of charge that occurs in a chemical bond because of differences in the electronegativities of the bonded atoms
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element with greatest electronegativity
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Flourine
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element with smallest electronegativity
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Francum
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more polar - Carbon oxygen bond or carbon-nitrogen bond?
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carbon oxygen
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how is a polar covalent bond similar to an ionic bond?
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gradual change
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why do nonpolar substances tend to boil at relatively low temperatures?
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only weak attractions between the molecules of a liquid; less heat is rquiredto liberate these molecules
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which tends to have a greater degree of symmetry:
a polar molecule or nonpolar molecule? |
polar
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which is stickier: polar or nonpolar molecules?
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polar
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primary difference between a chemical bond and an attraction between two molecules?
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chemical bond is much stronger
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which is stronger: the ion-dipole attraction or the induced dipole-induced dipole attraction?
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ion-dipole
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why are water molecules attracted to sodium chloride?
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opposite charges
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how are ion-dipole attractions able to break apart relativelystrong ionc bonds?
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a large number is needed
attractions exerted by the H2O molecules break the ionic bonds and pull the ions away from one another |
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what is a hydrogen bond?
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strong dipole-dipole attraction between a slightly positive hydrogen atom on one molecule &a pair of nonbonding electrons on another molecule
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are iduced dipoles permanent?
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temporary - when water is removed, molecules return to normal state
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why is it difficult to induce a dipole in a flourine atom?
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the atoms are very small & nonpolar
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why is the boiling point of octane so much higher than the boiling point of methane?
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methane molecules are easier to pull apart.
octane molecules are harder to pull apart b/c of so many induced dipole-induced dipole attractions |
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why is a ruby gemstone a solution?
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gemstones are solutions.
ruby is a solid solution of trace quantities of red chromium compounds in transparent aluminum oxide |
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distinguish between a solute and a solvent
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SOLUTE - any component in a solution that is not the solvent
SOLVENT - the component in a solution present in the largest amount |
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distinguish between a saturated solution and an unsaturated solution
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SATURATED - solution containing the maximum amount of solute that will dissolve
UNSATURATED - solution that will dissolve additional solute if it is added |
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how is the amount of solute in a solution calculated?
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concentration of solution X amount of solution
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is a mole a very large/small number?
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very large - 6.02 x 10^23
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by what means are ethanol and water molecules attracted to each other?
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ethanol is infinitely soluble in water; very attracted
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what effect does temperature have on the solubility of a solid solute in a liquid solvent?
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some are highlyaffected & some are mildly, depends on strength of chem bonds & the way molecules are packed together
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what effect does temperature have on the solubility of a gas solute in a liquid solvent?
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solubility decreases with increasing temp.
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what does it mean to say that two materials are infinitely soluble in each other?
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a solute that has no practical point of saturation in a given solvent
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what is the relationship between a precipitate & a solute?
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when a solution is saturated at a high temperature is allowed to cool, some of the solute usually comes out of the solution & forms precipitate
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what do oxgen molecules and perfluorodecalin molecules have in common?
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both nonpolar, readily mix
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which portion of a soap molecule is nonpolar?
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tail
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water and soap are attacted to each other by what time of attraction?
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dipole-induced dipole attractions
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what is the difference btween a soap and a detergent?
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synthetic soaps; stronger grease penetration & lower prics
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what component of hard water makes it hard?
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calcium & magnesium compouds
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why are soap molecules so attracted to calcium and magnesium ions?
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soap/detergent molecules give up their sodium ions to selectively bind w/ calcium or magnesium ions
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calcium and magnesium ions are more attracted to sodium carbonate than to soap. why?
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carbonate ion has 2 (-) charges & soap/detergent molecules have 1 (-) charge
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what accounts for the fact that ice is less dense than water?
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H2O molecule in the crystalline structure of ice occupy a greaer volume than in liquid h2o
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what is inside one of the open spaces of an ice crystal?
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nothing
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what happens to ice when great pressure is applied to it?
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open spaces collapse and liquid water is formed
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how is it pssible for a substance to melt & freeze at the same time?
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O^C is both the melting & freezing temp. for water
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what is released when a hydrogen bond forms between 2 water molecules?
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heat energy
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why does extracting heat from a mixture of ice & liquid water at 0C increase the rate of ice formation?
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allows hydrogen bonds to remain intact after they form & therefore there's tendency for ice crystals to grow
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why does adding heat to a mixture of ice & liquid water at 0C increase the rate of water formation?
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hydrogen bonds between H2O molecules are breaking, therefore more tendency for the ice crystals to melt
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why are soap molecules so attracted to calcium and magnesium ions?
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soap/detergent molecules give up their sodium ions to selectively bind w/ calcium or magnesium ions
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calcium and magnesium ions are more attracted to sodium carbonate than to soap. why?
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carbonate ion has 2 (-) charges & soap/detergent molecules have 1 (-) charge
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what accounts for the fact that ice is less dense than water?
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H2O molecule in the crystalline structure of ice occupy a greaer volume than in liquid h2o
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what is inside one of the open spaces of an ice crystal?
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nothing
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what happens to ice when great pressure is applied to it?
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open spaces collapse and liquid water is formed
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how is it pssible for a substance to melt & freeze at the same time?
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O^C is both the melting & freezing temp. for water
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what is released when a hydrogen bond forms between 2 water molecules?
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heat energy
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why does extracting heat from a mixture of ice and liquid water at O^C increase the rate of ice formation?
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allows hydrogen bonds to remain intact after they form & therefore there's tendency for ice crystals to grow
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why does adding heat to a mixture of ice and liquid water at freezing increase he rate of ice formation?
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hydrogen bonds are breaking; more tendency for the ice crystals to melt
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when the temp of O^C water is increased slightly - net expansion or contraction?
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contraction
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temperature at which competing effects of contraction & expansion produce the smallest volume of liquid water?
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4^C
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difference betwe cohesive & adhesive forces?
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cohesive - same substance
adhesive - 2 substance |
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in what direction is a water molecule on the surface NOT pulled?
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upward
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does liquid water rise higher in a narrow tube or a wide tube?
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narrow
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do all the molecules in a liquid have about he same speed?
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no, different speeds
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what phases are involved in sublimation?
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solid directly to a gas without being a liquid
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why is a burn from water vapor more dangerous than a burn from liquid water at the same temp?
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water vapor gives up considerable energy when it condenses to a liquid and wets the skin
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why do we feel uncomfortably warm on a hot, humid day?
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condensation outspaces evaporation & you feel the warming effects as vapor in the air condenses your skin
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pressure cooker - pressure or heat that cooks faster?
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pressure
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what condition permits water to boil at a temp below 100^C?
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atmospheric pressure
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is it easy or difficult to change the temperature of a substance that has a low specific heat
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easy
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substance that heats up quickly - high/low specific heat?
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high
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how does the specific heat of liquid water compare with the specific heats of other common materias?
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high specific heat
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Northeastern Canada & Europe - same amount of sunlight, yet Europe is generally warmer...
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water has a specific heat.
water from Caribbean is carried to North Atlantic, water releases energy while cooling, then water is blown over Europe |
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why is temp fairly consistent on islands & peninsulas?
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surrounded by water, therefore do not have the extreme temps like the interior of the continent
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when liquid water freezes, is heat released to the surroundigs or absorbed from the surroundings?
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released
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why doesnt the temp of melting ice rise as the ice is heated?
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At 0^C the temp stops rising
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how much heat is needed to melt 1 gram of ice?
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335 joules
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why is important that your finger be wet when you touch it to a hot iron?
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energy that ordinarily would go into burning your finger goes into changing the phase of the moisture from liquid to vapor
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why does it take so much more energyt boil liquid water than to melt ice?
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liquid to gas: +2259 joules per gram
solid to liquid: +335 joules per gram |
