AP CHEM WKST KEY: SOLIDS, LIQUIDS & GASES REVIEW

Transcription

1 AP CHEM WKST KEY: SOLIDS, LIQUIDS & GASES REVIEW 1) a) NaCl ionic b) C6H12O6 HB c) PH3 LF d) H2O2 HB e) CH3CH2OH HB f) HI DD g) Kr LF h) diamond covalent 2) a) H2O Want the strongest IMF for highest BP. H2O is polar with HB. H2S and H2Se are both polar with DD. H2O has the strongest IMF. b) HI Want the strongest IMF for highest FP. HCl, HBr and HI are all polar with DD. HI being the heaviest has the strongest IMF (LF). c) CH4 Want the weakest IMF for lowest BP. CH4, CH3CH3 and CH3CH2CH3 are all nonpolar with LF. CH4 being the lightest has the weakest IMF. d) NCl3 Want the weakest IMF for lowest FP. PCl3 is polar with DD. CCl4 and NCl3 are both nonpolar with LF. NCl3 is lighter than CCl4 and therefore has the weaker IMF. e) CH3OH Want the strongest IMF for highest surface tension. CH3OH is polar with HB. CH3CH2CH3 and CH3CH3 are both nonpolar with LF. CH3OH has the strongest IMF. f) PH3 Want the weakest IMF for the highest vapor pressure. NH3 is polar with HB. PH3 is nonpolar with LF. SbH3 is polar with DD. PH3 has the weakest IMF. g) H2O Want the strongest IMF for greatest viscosity. H2O is polar with HB. H2S and H2Se are both polar with DD. H2O has the strongest IMF. h) NH3 Want the strongest IMF for the greatest Hvap. NH3 is polar with HB. PH3 and AsH3 are both nonpolar with LF. NH3 has the strongest IMF. 3) Since water and glass are both polar there will exist attraction forces between the two. The adhesive forces will draw the water up on the glass, but the weight of the water in the tube is too much for the cohesive forces to bring up the middle of the water to the same level as the adhesive forces. Therefore, you get a meniscus. Mercury is nonpolar and will not be attracted to the glass. The rounded shape of the surface is due to the cohesive forces and surface tension. 4) Since glass is polar and polyethylene is nonpolar, the glass will have an attraction to the polar water molecules. Therefore, water will rise higher in a glass tube. It will rise until the weight of water in the tube (the force of gravity) is equal to the adhesive forces between the glass and the water. 5) A sphere has the least surface area per volume of all the geometric 3D shapes. 6) SF6 insoluble KNO3 soluble AlPO4 insoluble CH3CH2OH soluble CH3COCH3 soluble CH3CH2CH3 insoluble SO2 soluble CH4 insoluble HI soluble CH3Cl soluble 1

2 7) A: KE is increasing since temperature is increasing. Some of the energy goes to PE as well. B: No change in KE since temperature is not changing. Only PE changes here. C: KE is increasing since temperature is increasing. Some of the energy goes to PE as well. 8) (s) (l) critical pt critical temp critical pressure Pressure triple pt (g) Temperature You know this is for water since the boundary between the (s) and the (l) has a negative slope water is the only substance that does this since it is more dense as a liquid than a solid. 9) Supercooling is caused by the particles trying to line up as they freeze. Once they get organized, the temperature will increase slightly before leveling off at the freezing point. 10) triple point T C, P 4.58 torr critical point T 374 K, P 218 atm 11) a) C network b) CO molecular c) P4 molecular d) S8 molecular e) Mo metallic f) Pt metallic g) NH4Cl ionic h) BaS ionic i) Li2O ionic j) Xe Group 8A k) H2S molecular l) NaHSO4 ionic 12) a) network, ionic b) metallic c) metallic d) molecular e) molecular, Group 8A f) network g) metallic 2

3 13) a) C C is network, NaCl is ionic, and CO2 is molecular. Network generally has higher melting points than ionic. b) I2 Na is metallic, I2 is molecular, and BaCl2 is ionic. Molecular substances generally have the lowest melting points of these three types. c) Fe SiO2 is network, Fe is metallic, and CaO is ionic. Metallic solids are the best electrical conductors because of the electron sea of its structure. SiO2 is a semiconductor of electricity, and CaO will only conduct electricity when melted or dissolved in some solvent. 14) ln ( P vap1 P vap2 ) H vap R ( 1 T 2-1 T 1 ) 125 torr ln ( mol J mol K 760 torr ) J ( T K ) K ( 1 T K 1 ) 5.14 x 10 4 K 1 1 T K K 1 1 T 2 T K 15) ln ( P vap1 P vap2 ) H vap R ( 1 T 2-1 T 1 ) x ln ( 760 torr ) J x ln ( 760 torr ) x 760 torr x 263 torr mol J mol K 1 ( K K ) 16) nλ 2d sinθ d nλ 2 sinθ (2)(162 pm) 426 pm (2)( sin ) 17) assume n1 nλ 2d sinθ λ 2d sinθ n (2)(1.45 Å)(sin 15.4 ) Å 77.0 pm 1 3

4 18) 15.0 C 0 C: q mc(s) T (100.0 g)(2.08 J g C )(15.0 C) 3120 J 3.12 kj melting: 1 mol H2O 6.07 kj H g H2O ( ) ( ) 33.7 kj g H2O 1 mol H2O 0 C 100 C: q mc(l) T (100.0 g)(4.184 J g C )(100 C) J kj boiling: total heat thus far: 1 mol H2O 40.7 kj H g H2O ( ) ( ) 226 kj g H2O 1 mol H2O kj After boiling and becoming a gas, the amount of heat is only kj, far less than the kj of heat added. Therefore, the water is a gas. 19) H2S g/mol SO g/mol You would smell the rotten egg smell of H2S first since it is lighter and travels faster. 20) Cl2 < NO2 < H2S < N2 < C2H2 < CH4 (the lighter the gas molar mass the faster it goes) 21) - Gas particles do have a volume and thus decreases the available volume of the container for other particles. - Gas particles do exhibit attraction forces which cause the particles to slow down and collide with the container s surface less often and thus has a lower pressure than expected. 22) at high T and low P 23) van der Waals adjusted the V to compensate for the V of the particles. He also adjusted the P to account for fewer collisions against the surface due to attractive forces between the particles. 24) a) As temperature increases the KEave also increases. NOTE: All gases at the same T will have the same KEave. b) As temperature increases the average velocity of the gas particles also increases. c) The lighter the gas the faster its velocity. 25) a) Since they all have the same temperature, they all have the same KE. b) Flask A CO2 is the heaviest of the 3 gases and therefore the slowest moving. 4

5 26) a) inversely proportional d) directly proportional b) directly proportional e) directly proportional c) directly proportional 27) a) volume will increase b) pressure remains the same c) KEave increases d) number of collisions per square inch remains the same (pressure doesn t change) 28) a) volume doesn t change b) pressure increases c) KEave increases d) number of collisions per square inch increases 29) a) interstitial alloy small atoms occupy the interstices (small holes) of the closest packed structure of a metal e.g. steel b) substitutional alloy some of the host metal atoms are replaced by other metal atoms of similar size. e.g. brass, bronze, sterling silver, pewter, plumber s solder 30) Diamonds and graphite are both network solids with directional covalent bonds between the atoms. They are different in that diamonds have a tetrahedral arrangement around each C atom whereas graphite has a trigonal planar arrangement around each C atom. Thus, graphite forms layers with LF between the layers to hold the solid together. diamond graphite 31) Silica is the fundamental silicon-oxygen compound, which has the empirical formula SiO2 arranged in a tetrahedral structure (each cell is SiO4) in the crystal, and forms the basis of quartz and certain types of sand. 32) Silicates are similar to silica in that they too are unit cells of SiO4 but unlike silica, silicates have an O:Si ratio greater than 2:1 and contain silicon-oxygen anions bonded to metal cations (see figure 10.27, p. 460). Silicates are found in most rocks, soils, and clays. Silicates are also used in ceramics and are responsible for the hardening characteristics found in ceramics. 5

6 33) KEave 3 2 RT 3 2 ( J mol K )(392 K) 4890 J mol 1 34) u rms 3RT J M 3( )(296.2 K) mol K kg mol urms ms 1 35) rate O 2 rate N 2 O 5 MM N 2O 5 MM O g g O2 is times faster than N2O5 36) rate He rate unk MM unk MM He ml min ml min -1 x 4.00 g x 4.00 g x g x 29.6 g 37) V ml P torr torr torr T C K V2? P2 760 torr T K P 1 V 1 T 1 P 2V 2 T 2 P1V1T2 P2V2T1 V 2 P 1V 1 T 2 P 2 T 1 ( torr)(300.0 ml)( K) (760 torr)(295.2 K) V ml 38) g? NH3 V L T 12.5 C K P inhg atm PV grt MM g PV(MM) RT (1.019 atm)(20.00 L)(17.04 g mol ) ( L atm mol K )(285.6 K) g g 6

7 39) a) 10.0 L NH 3 ( 3 mol H 2 2 mol NH 3 ) 15.0 L H 2 1 mol Zn b) 25.0 g Zn ( g Zn ) (1 mol H 2 1 mol Zn ) (22.4 L H 2 ) 8.57 L H 1 mol H 2 2 c) kpa atm 36.5 C K PV nrt V nrt P L atm (1 mol)( mol K )(309.6 K) atm L 1 mol Na 23.0 g Na ( g Na ) (1 mol H 2 1 mol Na ) (26.0 L H 2 ) 26.0 L H 1 mol H ) g He 5.00 mol He 5.00 g O mol O mol total P total n total P He n He P He (P total )(n He) n total (770.2 torr)(5.00 mol) mol 747 torr He 41) torr atm 25.0 C K d P(MM) RT (1.053 atm)(44.01 g mol ) ( L atm mol K )(298.2 K) g L 42) 3.25 x O2 molecules 43) V L T C K V L T2? V 1 T 1 V 2 T 2 V1T2 V2T1 T 2 V 2T 1 (4.40 L)( K) V L T2 142 C 415 K 44) 2NO2(g) + H2O(l) HNO2 + HNO3 2SO2(g) + O2(g) 2SO3(g) SO3(g) + H2O(l) H2SO4 45) CaCO3(s) + 2HNO3 Ca(NO3)2 + CO2(g) + H2O(l) CaCO3(s) + H2SO4 CaSO4 + CO2(g) + H2O(l) 7

8 46) a) NO is emitted into the air by vehicle exhaust and then is oxidized into NO2. b) NO2(g) sunlight NO(g) + O(g) c) O(g) + O2(g) O3(g) forms ozone O(g) + H2O(l) 2OH d) NO(g) + ½ O2(g) NO2(g) e) NO2(g) + OH HNO3 (OH also reacts with other stuff to form other harmful substances) end result smog is the result of the production of O3, HNO3, and other stuff formed by OH 47) -combustion of petroleum CO, CO2, NO, NO2 and others (including unburned fuel) -combustion of coal SO2 which leads to H2SO4 (acid rain) 8