KEY: Fall 2014 Chemistry Final Review Matter and Change Measurement and Calculation Density of ethanol [g/ml] Trial A Trial B Trial C

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1 Name: Date: Perid: KEY: Fall 2014 Chemistry Final Review Matter and Change 1. What is a hmgeneus mixture? Give an example. What is a hetergeneus mixture? Give an example. Hmgeneus: a physical cmbinatin f 2 r mre pure substances that has a unifrm appearance; als knwn as a slutin; Ex. gatrade. Hetergeneus: a physical cmbinatin f 2 r mre pure substances that has a nnunifrm appearance (layers, different clrs, etc); Ex. Italian salad dressing 2. Describe the three states f matter. (Mtin f particles? Energy? Definite/indefinite vlume? Shape?) Slid: particles are clse tgether, vibrate in place, definite shape and vlume, least energy. Liquid: particles are able t slide past each ther, mve mre rapidly, indefinite shape, definite vlume, intermediate energy. Gas: particles are widely spaced, mve arund very rapidly, indefinite shape and vlume, highest energy g f hydrgen perxide decmpses int 34.6 g f water and xygen gas releasing heat. What mass f xygen is released? Is the reactin endthermic r exthermic? 19.6 g; exthermic 4. What is mass? What is weight? Which quantity wuld remain the same if yu traveled t the mn? Mass: measure f the amunt f matter in an bject. Weight: measure f the pull f gravity n the mass f an bject. Mass Classify the fllwing as a chemical r physical change and give a reasn fr each. 5. Meat spiling Chemical 6. Dry ice subliming Physical 7. Candle wax melts Physical 8. Metal crrdes Chemical Classify the fllwing as an element, cmpund r mixture. 9. NaCl(aq) Mixture (salt and water frm a slutin) 10. Sugar Cmpund (pure substance; fixed chemical frmula) 11. O 2 (g) Element (n Peridic Table) 12. Of elements, cmpunds, and mixtures, which can be separated by physical means? Which by chemical? Mixtures are separated by physical methds, cmpunds are separated by chemical reactins, and elements cannt be separated by either means. They are already at the level f individual atms. Classify the fllwing as a physical r chemical prperty. 13. Salt disslves in water. Physical Prperty 14. Acid deterirates marble. Chemical Prperty 15. Isprpyl alchl is flammable. Chemical Prperty Classify the fllwing as intensive r extensive 16. Density Intensive 17. Mass Extensive 18. Vlume Extensive 19. Melting pint Intensive Measurement and Calculatin 20. What metric unit wuld be apprpriate fr estimating the height f the SLHS Christmas tree? The mass f yur chemistry bk? The vlume f a cup f apple cider? Meter; kilgram; milliliter 21. Define precisin and accuracy. Precisin: the reprducibility f measurements; hw clse measurements are t each ther. Accuracy: the crrectness f a measurement; hw clse measurements are (averaged) t the crrect answer. 22. A grup gathered the fllwing data: Density f ethanl [g/ml] Trial A Trial B Trial C Grup Grup Grup Grup

2 Describe the accuracy and precisin f each grup if the crrect density is 0.87 g/ml. Gp. 1: precise, nt accurate; Gp. 2: nt precise, mderately accurate; Gp. 3: precise, accurate: Gp. 4: nt precise, accurate (because the average f the trials matches the actual density) 23. A sample f metal has a mass f 25 g and a vlume f 12 cm 3. What is its density? 2.1 g/cm Rund t three significant figures OR 3.63 x Rund t 4 significant figures OR x The number f significant figures in is: The number f significant figures in is: The number f significant figures in is: Express the fllwing calculatin t the prper number f significant figures: = Express the fllwing calculatin t the prper number f significant figures: (3.56 x )/220 = OR 1.1 x Cmpare and cntrast a tn f feathers and a tn f bricks in terms f mass, matter, vlume, and density. Mass: Same; Vlume: Feathers have mre vlume; Density: Bricks have higher density. 32. A student perfrms an experiment t determine hw the freezing pint f water is affected when varius amunts f salt are added t it. The student discvers that the freezing pint decreases. The student cncludes that the salt disturbs the hydrgen bnding in water, making it mre difficult fr the mlecules t adhere t each ther and freeze. Is this a valid cnclusin based n the data? Why r why nt? N. The data nly supprts the trend that the freezing pint decreases, but des nt prvide any evidence as t why. 33. Interval: 0.1 cm Reading: 1.37 cm 34. Interval: 1 ml Reading: 36.5 ml Dimensinal Analysis 35. Cnvert 0.68 mg t g g OR 6.8 x 10-4 g 36. Cnvert 18.9 hm t m m 37. Cnvert 1036 kg t cg. 103,600,000 cg OR x 10 8 cg 38. Cnvert 9.6 m t dm. 96 dm 39. Cnvert 8.77 dam t cm cm 40. Cnvert cm 3 t L L 41. Hw many secnds are in 3 days? 259,200 s (3 x 10 5 s with SF) 42. Hw many minutes are in 1 year? 525,600 min. (5 x 10 5 s with SF) 43. Hw many teaspns are in 2 cups? 96 t. (100 t with SF) mi. = km. Cnvert the speed f light (3.0 x 10 8 m/s) t mi/hr. 6.7 x 10 8 mi/hr 45. A primitive sciety uses a barter system t purchase gds. A farmer wants t exchange his crn fr a new dairy cw. Hw many bushels will he need? 133 bushels (SF d nt apply here; exact cunted bjects) 1 cw = 95 baskets f pears; 4 baskets f pears = 42 tubs f butter; 2 bushel f crn = 15 tubs f butter 46. A metal has a density f 3.8 g/cm 3. Hw many L f water will a 38 kg sample f the metal displace? 10. L 47. If a penny has a radius f 12 mm, hw many pennies wuld it take lined up edge t edge t stretch acrss a rm 15 m wide? 625 pennies (630 pennies with SF) 48. A fabric csts $13.99/yd. Hw much des it cst per meter? 1 inch equals 2.54 cm. $15.30 / m Atmic Structure 49. Describe the structure f an atm. What is it cmpsed f? An atm is cmpsed f a dense but tiny nucleus surrunded by an electrn clud. The nucleus cntains the prtns (psitive) and neutrns (neutral). 50. Cmpare and cntrast the subatmic particles f an atm. Prtns: psitive charge, abut 2000 x as massive as an electrn, abut equal t the mass f a neutrn; Neutrns: neutral, see abve; Electrns: negative charge, see abve. 51. What is the smallest part f an element that retains the prperties f that element? atm 52. What accunts fr the majrity f the atm s mass? Its vlume? Mass nucleus; Vlume electrn clud 53. Define istpe. What remains the same between tw istpes f the same element? Istpe: atms f the same element that have different numbers f neutrns. # prtns and # electrns stay the same (as d chemical prperties) 54. What are tw ways t express the istpe f an atm with 15 prtns and 16 neutrns? Phsphrus 31 & P

3 55. What are tw ways t express the istpe f an atm with a mass number f 80 and 35 electrns? Brmine- 80 & 80 35Br 56. What atm has an average atmic mass in nature f apprximately 24 amu? A magnesium atm 57. Describe the gld fil experiment. Wh perfrmed it? What part f the atm was discvered because f it? Rutherfrd perfrmed the gld fil experiment. He sht a stream f alpha particles at a thin sheet f gld fil, expecting them t pass thrugh undeflected. Hwever, several particles were significantly deflected and sme bunced straight back. This led t the cnclusin that the psitive charge in an atm was nt spread evenly thrughut but cncentrated in a nucleus (this is the nly way there wuld be smething massive enugh in the atm t cause the relatively large alpha particle t be deflected). Thus, the nucleus was discvered. 58. Carbn exists as carbn-12 and carbn-14. Which istpe ccurs in greater abundance? Explain. Carbn-12. The average atmic mass f carbn is amu which is weighted much mre twards 12 than 14, indicating that there is mre f 12 than 14 in the average. 59. Determine the average atmic mass f nen, cmpsed f nen-20 (mass amu and 90.15%), nen-21 (mass amu and 0.27%), and nen-22 (mass amu and 9.22%) amu 60. An atm f I has a mass number f 127. Hw many neutrns des it cntain? What is the atmic number f ptassium-39? The mass number? The number f neutrns? 19; 39; An atm has atmic number P and mass number M. Hw many neutrns des it have? Neutrns = M - P 63. Define radiactive decay. A prcess in which certain istpes f sme elements spntaneusly break dwn t prduce a smaller element alng with particles (alpha, beta) and energy (gamma radiatin). 64. Define half-life. The time during which a given atm f a radiactive istpe has a chance f decaying OR the time it takes fr half f a sample f a radiactive istpe t decay. 65. Is the half life the same fr all atms f a specific radiactive istpe? Fr all istpes f different elements? Yes; fr example, all atms f carbn-14 have the same half-life. N; each radiactive istpe has a unique half-life different frm thers. Fr example, carbn-14 has a different half-life than cbalt Determine the riginal and final amunts fr the fllwing: Half-life Time Elapsed Original Amunt Final Amunt 35 s 70 s 100 g 25 g 20 min 2 hurs 38.4 g 0.6 g 1.6 days 8 days 6000 mg mg 4 years 16 years 120 g 7.5 g Define alpha (α) particles and knw the symbl. A helium nucleus; 2 He 68. Define beta (β) particles and knw the symbl. A high-speed electrn; 0 1e 69. Write the cmplete reactin fr the fllwing radiactive decay prcesses: Alpha: M He Zr Li He H Md He Es Beta: 92 U 1e+ 93Np Pa 1e 92U 89 Ac 1e+ 90Th 70. What is a mle equal t? Hw is it related t the average atmic mass f an element? 1 ml = 6.02 x particles; the mass f a mle f an element is equal t its average atmic mass with the unit f gram instead f amu. Electrns in Atms 71. The maximum number f electrns that can ccupy the 4 th energy level is? 32 (nifty trick: 2n 2, where n = the energy level. Be aware that this is purely theretical, and the larger energy levels may never hld their max capacity because even ur largest atms are nt large enugh t supply that number f electrns). 72. Name and explain the 3 rules that describe hw electrns enter an atm s rbitals. Aufbau Principle: electrns enter rbitals f lwest energy first and build up frm there (fllw the Aufbau rder). Hund s Rule: single electrns enter all rbitals f equal energy with spins parallel first, befre electrns are paired in the same rbital. Pauli Exclusin Principle: N mre than 2 electrns may ccupy the same rbital, and electrns in the same rbital must have ppsite spins. 73. The electrn cnfiguratin fr the element with atmic number 12 is? Atmic number 24? 1s 2 2s 2 2p 6 3s 2 ; 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d Hw many valence electrns des S have? Cl? K? Kr? 6; 7; 1; 8

4 75. An element has electrn cnfiguratin: 1s 2 2s 2 2p 6 3s 1. What is the atmic number f the element? Draw an rbital diagram fr phsphrus. 1s 2s 2p 3s 3p 77. Draw an electrn dt diagram fr phsphrus. What d the dts represent? Valence electrns What is the maximum number f d electrns in the 4 th energy level? What is the maximum number f p rbitals in the 3 rd energy level? The first energy level t have an ccupied f rbital is? An atm has electrns in the 3p, 2p, 3s, 2s, and 1s rbitals. Which electrns are at the lwest energy? Thse in the 1s 82. Calculate the wavelength (in meters) f radiatin with a frequency f 5.00 x Hz. In what part f the electrmagnetic spectrum will this radiatin be fund? (speed f light prvided n test) 6.00 x 10-7 m r 600 nm. Visible prtin; yellw light (cnsult EM spectrum chart in ntes; d nt memrize chart) 83. A certain surce f radiatin emits a wavelength f nm. What is the energy in J? (speed f light and Planck s cnstant prvided n test) 3.98 x J 84. What is a phtn? Quantum packet f light, a particle f light 85. Arrange the types f electrmagnetic radiatin in rder f increasing wavelength? Increasing frequency? Increasing energy? Wavelength: gamma, x-rays, UV, vilet-red, infrared, micrwave, radi; Frequency: ppsite; Energy: same as frequency Peridic Trends 86. In general, metals have (few/many) valence electrns and they (lse/gain) electrns t becme stable. Nnmetals have (few/many) valence electrns and they (lse/gain) electrns t becme stable. 87. Define inizatin energy, and state the trend dwn a grup and acrss a perid. The amunt f energy required t remve an electrn frm a gaseus atm, prducing a psitively-charged in (catin). Dwn a grup, inizatin energy decreases. Acrss a perid, inizatin energy increases. 88. State the trend fr atmic radius acrss a perid, and explain WHY the trend is bserved. Atmic radius decreases acrss a perid, because increasing nuclear charge pulls the electrn clud in tighter t the nucleus. 89. State the trend fr atmic radius dwn a grup, and explain WHY the trend is bserved. Atmic radius increases dwn a grup, because added energy levels increases the size f the electrn clud. 90. Wh is credited with develping the first peridic table? What prcedure did he use? Dmitri Mendeleev. He cllected infrmatin n the prperties f the elements and wrte them n cards. He arranged the cards int a pattern that gruped elements with similar prperties int the same clumns, while placing them in rder f increasing atmic mass. 91. Henry Mseley realized that Mendeleev s peridic table was actually arranged in rder f increasing atmic number. 92. State the peridic law. The physical and chemical prperties f the elements are peridic functins f their atmic numbers. 93. Elements in the same grup in the peridic table can be expected t have similar prperties. 94. Describe the halgens in terms f electrn cnfiguratin pattern and prperties. Cnfigs end in s 2 p 5. They are the mst reactive nnmetals and react with metals t frm salts (inic cmpunds). 95. Describe the alkali metals in terms f electrn cnfiguratin pattern and prperties. Cnfigs end in s 1. They are the mst reactive metals, are shiny and sft, are nt fund uncmbined in nature, and are typically stred in il. 96. Describe the nble gases in terms f electrn cnfiguratin pattern and prperties. Cnfigs end in s 2 p 6. They are largely unreactive (resist frming cmpunds) because they have an ctet f valence electrns. 97. Define electrnegativity, and state the trend dwn a grup and acrss a perid. Electrnegativity is the tendency f an atm in a cmpund t attract the bnding electrns t itself. Dwn a grup, electrnegativity decreases. Acrss a perid, electrnegativity increases..p..

5 98. Based n #97, what is the mst electrnegative element n the peridic table? The least (excluding nble gases)? Flurine, francium. Chemical Names and Frmulas 99. The individual particles f an inic cmpund are called frmula units The individual particles f a mlecular cmpund are called mlecules Define a catin and an anin. A catin is a psitively charged in; an anin is a negatively charged in List the prperties f inic cmpunds. Cmpsed f metal and nnmetal ins (and/r plyatmic ins), particle = frmula unit, inic bnding (mre prperties t cme 2 nd semester). Nmenclature f inic cmpunds requires that ttal charge equal t zer. Frmulas are written as lwest whle number rati f ins; Rman numerals are used n multivalent metals List the prperties f mlecular cmpunds. Cmpsed f nnmetals and smetimes metallids, particle = mlecule, cvalent bnding (mre prperties t cme 2 nd semester). Nmenclature f mlecular cmpunds requires the use f prefixes t represent the number f atms f each type in the mlecule State the # f electrns lst r gained when these elements frm ins: K, Br, Al, S 1 lst, 1 gained, 3 lst, 2 gained 105. State the # f electrns lst r gained when these elements frm ins: Ca, O, Na, N 2 lst, 2 gained, 1 lst, 3 gained 106. What is the frmula fr silver sulfide? Ag 2 S 107. What is the frmula fr lead (IV) phsphate? Pb 3 (PO 4 ) What is the frmula fr barium sulfate? BaSO What is the frmula fr tetraphsphrus decxide? P 4 O What is the name fr HNO 2? nitrus acid 111. What is the name fr H 2 CO 3? carbnic acid 112. What is the name fr Cu 2 O? cpper (I) xide 113. What is the name fr N 2 O 5? dinitrgen pentxide Quantifying Cmpunds 114. What is the definitin f mlar mass? What is the prper unit? The mass in grams f 1 mle f a substance. Unit = g/ml 115. What is the mlar mass f Al 2 (SO 4 ) 3? g/ml 116. Hw many mles f ptassium hypchlrite are present in 45.0 g f ptassium hypchlrite? ml 117. Hw many nitrate ins are present in 3.00 ml f cpper (II) nitrate? 3.61 x NO 3 - ins 118. Hw many hydrxide ins are present in 1 frmula unit f aluminum hydrxide? 3 OH - ins 119. Hw many flurine atms are present in 1.50 ml carbn tetrafluride? 3.61 x F atms 120. Hw many mlecules f sulfur dixide are present in 4.25 g sulfur dixide? 3.99 x SO 2 mlecules 121. What is the percentage cmpsitin f glucse, C 6 H 12 O 6? 40.0% C, 6.7% H, 53.3% O 122. What is the mass f xygen in 34.5 grams f ptassium chlrate? 13.5 grams xygen 123. What is the empirical frmula fr a cmpund that is 32.4% sdium, 22.5% sulfur, and 45.1% xygen by mass? Na 2 SO What is the empirical frmula fr a cmpund that is 54.5% carbn, 9.1% hydrgen, and 36.4% xygen by mass? C 2 H 4 O 125. The mlecular frmula fr butene is C 5 H 10. What is its empirical frmula? CH The empirical frmula f a cmpund is NO 2. Its mlar mass is g/ml. What is the mlecular frmula f the cmpund? N 2 O The empirical frmula f a cmpund is C 4 H 10 O. Its mlar mass is g/ml. What is the mlecular frmula f the cmpund? C 12 H 30 O 3 Chemical Reactins 128. What symbls are used in chemical equatins t indicate heat added? A catalyst? Triangle abve arrw; chemical frmula fr catalyst abve arrw 129. Balance the equatin: 2 C 3 H O 2 6 CO H 2 O 130. Balance the equatin: P 4 O KOH 4 K 3 PO H 2 O

6 Pre-AP Chemistry KEY: Supplement t Exam Review: Fall List the Metric System frm Giga- thrugh nan-. Give the prefix abbreviatins and meanings in relatin t the base unit. giga mega kil hect deka BASE deci centi milli micr nan G M k h da --- d c m µ n r 1 2. List 6 categries f energy (frm the Matter and Change unit), and define each. Kinetic: energy f mtin (mving car) Radiant: light energy Ptential: energy f psitin (rck n hill) Chemical: energy stred in chemical bnds Thermal: heat energy Nuclear: energy stred in the nucleus f atms 3. Give an example f hw chemical ptential energy culd be cnverted t kinetic energy. Fds cntain carbhydrate, fat, and prtein mlecules. These mlecules cntain chemical ptential energy stred in the chemical bnds. When the fd is digested, the mlecules are brken dwn and the energy in the bnds is cnverted t ther frms. Sme f this energy is used fr the physical prcesses yu d, such as walking t each f yur classes n a schl day (kinetic energy). 4. List and define the 6 phase changes. State whether each is an endthermic r exthermic prcess. Remember: if energy is absrbed (ging t a higher energy state f matter), the change is endthermic. If energy is released (ging t a lwer energy state f matter), the change is exthermic.

7 5. Are phase changes physical r chemical changes? Defend yur answer. They are all physical changes. The chemical identity f the material des nt change during a phase change; nly the state f matter changes (see #2 n p. 1 f review). Fr example, ice, water, and steam all have the same chemical frmula, H 2 O. 6. Define cnductin, cnvectin, and radiatin, and give an example f each. Cnvectin: the transfer f heat energy in a gas r liquid (nt in slids) by mvement f currents. The heat mves with the fluid. Example: At the beach, ht air rises, cler air frm the cean cmes in t replace it, and then the cl breeze cls yur bdy. Cnductin: the transfer f heat energy thrugh matter frm particle t particle (the materials are actually tuching during the transfer). Cnductin is mst effective in slids, but it can happen in fluids. Example: A chemical reactin ccurring inside a test tube causes the test tube t heat up. Radiatin: the transfer f heat energy by electrmagnetic waves. Radiatin is the nly frm f heat transfer that can ccur in empty space, withut the aid f any slids, liquids r gases. Sunlight is a type f electrmagnetic wave. It travels thrugh space via radiatin. Example: A lamp spreads light thrugh a rm. 7. D mini-marshmallws flat in ht chclate? What abut regular marshmallws? What abut the Stay-Puft Marshmallw Man (frm Ghstbusters), given a large enugh mug? Explain yur answers, and relate it t density as an intensive prperty. All sizes f marshmallws will flat in ht chclate, because they all have the same density. If yu had a large marshmallw and cut it int little pieces, each piece wuld have the same density as the riginal piece, because the mass and vlume bth decrease by the same prprtin, and D = m/v. Since density des nt change with the amunt f the substance, it is classified as an intensive prperty. Interesting nte: Fluctuatins in temperature can result in changes in the density f a substance, especially if the temperature change causes a change in the state f matter! 8. List the 5 cmpnents f Daltn s Atmic Thery. What parts have nw been crrected, based n infrmatin we have acquired since the time f Daltn? All matter is cmpsed f extremely small particles called atms. Atms f the same element are identical and have the same prperties; atms f different elements have different prperties. Atms are indivisible and indestructible. Atms cannt be created, destryed, r changed int anther element. Atms f different elements cmbine in whle number ratis t frm cmpunds. This is knwn as the Law f Definite Prprtins. When atms react, they can smetimes cmbine in mre than ne whle number rati t frm different cmpunds. This is knwn as the Law f Multiple Prprtins. Since Daltn s time, we have learned mre abut the atm, prviding mre infrmatin abut pints 2 and 3 abve: Atms are divisible int even smaller subatmic particles (prtns, neutrns, electrns). Atms f the same element are nt all identical. They can have different masses because they differ in the number f neutrns. These varieties f ne element are called istpes f that element. During nuclear reactins (which are fundamentally different frm chemical reactins), it is pssible fr ne atm t be transfrmed int a different type f atm.

8 9. Describe the Bhr Mdel f the atm, and state the flaw in the mdel, based n what we nw knw t be true. Electrns are restricted t specific energies and fllw paths called rbits a fixed distance frm the nucleus. This is similar t the way the planets rbit the sun. Hwever, the quantum mdel later shwed that electrns d nt have neat rbits like the planets. 10. Describe the current mdel f the atm: The Quantum Mechanical Mdel. It is a mathematical mdel. It was develped in the 1920s by the wrk f many scientists, including de Brglie, Schrödinger, Pauli, and Heisenberg. In the quantum mdel, electrns are described as standing waves f energy. Electrns exist in regins f space arund the nucleus which are called rbitals. The paths f the electrns within the rbitals are randm and therefre cannt be predicted. We can nly talk abut the prbability f an electrn being in a certain regin. Electrns have a high prbability f being lcated near the nucleus. 11. Define alpha particles, beta particles, and gamma radiatin, and give the characteristics f each. Alpha: helium nucleus Beta: high speed electrn Gamma: energy Mre massive Less massive N mass; all energy Cause the mst damage ver a shrt Cause less damage ver a shrt range Cause the least damage ver a shrt range Least able t penetrate surfaces; stpped by a piece f paper Mre able t penetrate surfaces; stpped by a thin sheet f aluminum fil range Mst able t penetrate surfaces; stpped by a thick sheet f lead 12. Cntrast nuclear fissin with nuclear fusin: Write equatins fr bth prcesses and state the uses and/r where each reactin is bserved. Fissin: Fusin: Fissin reactins were develped during WWII fr use in nuclear weapns (uranium r plutnium fuel). Currently, they are used as the energy surce in nuclear pwer plants. Fusin reactins ccur n the stars, including ur sun. They liberate 3-10x mre energy than fissin reactins, and d nt generate nuclear waste, but we have nt yet fund a way t carry ut fusin reactins in an efficient way n earth. 13. Give the reasns why bth the grup and peridic trends fr inizatin energy are bserved. Inizatin energy (IE) decreases dwn a grup, because the shielding effect makes it easier t remve an electrn. IE increases acrss a perid, because increasing nuclear charge results in mre tightly held electrns, requiring mre energy t remve. 14. Give the reasns why bth the grup and peridic trends fr electrnegativity are bserved. Electrnegativity (EN) decreases dwn a grup, because the shielding effect makes it mre difficult fr the nucleus t attract bnding electrns t itself. EN increases acrss a perid because increasing nuclear charge results in a strnger attractin fr the bnding electrns. 15. What is the sum f all cefficients when the fllwing equatin is balanced: Prpene gas (C 3 H 6 ) is burned in xygen gas t prduce carbn dixide and water = Hw many atms f nitrgen are in 7.50 L f nitrgen gas at STP? 4.03 x atms f N (remember that the representative particles f nitrgen gas are diatmic mlecules)