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2 PART A. (4 Pints each) Chem 11/15 Exam #1 Fall 01 Day Test 1. A piece f metal has a mass f kg and a density f 19. g/cm. Determine the vlume f the metal. a cm mass mass 1, 696g b cm density ; vl 87.9cm vl density 19. g/ cm c..7 cm d. >100 cm e. < 1 cm. Hw many es f carbn dixide are present in 5.5 g f carbn dixide? a. 0.5 e b. 0.5 e c. 1.8 e d. 0.1 e e. 8.0 e. A student perfrms an experiment t determine the density f a sugar slutin. She btains the fllwing results: 1. g/ml, 1.4 g/ml, 1. g/ml, 1.5 g/ml. If the actual value fr the density f the sugar slutin is 1.1 g/ml, which statement belw best describes her results? Her results are a. accurate, but nt precise. b. precise, but nt accurate. c. bth precise and accurate. C 1 g/ ; O 16 g/ ; CO 1 x16 44 g/ 5.5gCO x g d. neither precise nr accurate. e. It is nt pssible t determine with the infrmatin given. 4. Hw many silver atms are cntained in 54 grams f silver, Ag? a b c d e The crrect frmula f Barium phsphate is g g x atms x x.0x10 atms a. BaPO 4 b. Ba PO The xidatin state f Cr in KCrO is 4 a. + b. +4 c. Ba PO 4 d. Ba (PO 4 ) c. +6 d. +7 e. Ba (PO 4 ) 1 y4 1; y6 e A certain hydrcarbn has a ar mass f 18g/ and is 9.71% C and the remainder is hydrgen. What is its ecular frmula? a. C 8 H gC x C b. C H 4 1 1g c. C 5 H 1 6.9gH x H d. C 10 H g e. C 5 H 4 51 x 41 x 64; 18/64

3 Chem 11/15 Exam #1 Fall 01 Day Test 8. Hw many prtns and electrns are in the fllwing element? a. p+ = 1, e- = 18 b. p+ = 1, e- = 0 c. p+ = 19, e- = 1 d. p+ = 19, e- = 0 e. p+ = 19, e- = Fr the fllwing reactin, hw many es f B are required t make 15g f C? a. 0.4 B b B c. 1. B d. 7. B e B 4A B 5C D g/ gc 1 x C x B = B 1 44g 5 C 10. Fr the abve reactin, 0.74 es f A react with 0.44 es f B. When 0.16 es f B are left, hw many es f A are left? a. 0.1 b c I 4A B 5C D d C -4x -x e E 0.16 S, x = 0.16; x =0.14; es A= = 0.18 es g f a gasline with a density f 0.68 g/cm spills n a pnd. It spreads ut n the surface f the pnd t cver 0 m. Hw thick is the layer in nanmeter? (1 nm= 10-9 m r 10 9 nm = 1 m.) a..6 x10 7 nm b. 60 nm c. 10 nm d. 1. x10 7 nm e. Nne f the abve is crrect t sig. fig. mass mass.5g density ; vl 5.15cm vl density 0.68 g / cm 9 vl 5.15cm 1m 10 nm t x area vl; t x x 57 60nm area 0m 10 cm m 1. The ar mass f magnesium nitrate is abut 148. g/. What is the mass f xygen in 15 g f magnesium nitrate? a. 11 g Frmula : Mg NO b. 4.9 g 15g MgNO Mg NO 6 O 16gO c g x x x 9.7gO g MgNO O d. 19 g e. 9.7 g

4 Chem 11/15 Exam #1 Fall 01 Day Test 1. The warmer the male cricket, the faster its metablism and the faster it chirps. The temperature in Fahrenheit can be determined frm the chirp rate using the fllwing experimental frmula: T = 50 + (N - 40) / 4 where N is the number f chirps per minute. If the chirp rate increases frm. chirps per secnd t.5 chirps per secnd, what is the increase in temperature in degrees Celsius? a. 7 b. 9 c. 11 d. 1 e. 15 f i T 50 N 40 /4 50 N 40 /4 N/4.5 chirps. chirps 60sec 78chirps N x 1sec 1sec 1min min 1 C T N/ F C 1.8 F 14. When cnsidering significant figures, which f the fllwing answers is crrect? a. 60 b. 61 c d e / = = Which f the fllwing is clsest t the mass percent f flurine in CCl CF? a. 10% b. 0% c. 0% d. 40% e. 50% MM CClCF 1.0 x 5.45 x 19.0 x g / 19.0 x g/ % F x100% 0.% g/ 16. Calculate the atmic mass f hypthetical element "X", if it has naturally ccurring istpes with the fllwing natural abundances and masses: a amu b amu c amu d amu e amu 0.88% is X-44 with amu the rest is X-49 with amu 0.088x x

5 Chem 11/15 Exam #1 Fall 01 PART B Shw wrk (Each prblem is 1 pts) I. Three independent questins. Day Test (a) (4 pts) Hw many hydrxide ins, OH, are in 5.0x10 ml f 0.8 M NaOH? L 1 OH L x ins x x.5x10 inx (b) (4 pts) Cmplete and balance the fllwing cmplete cmbustin reactin using smallest integers: CHOH O 5 5 CHOHO g CO H O (c) (4 pts) Cmplete and balance the fllwing precipitatin reactin using smallest integers. Nte, yu must include (aq) fr the spectatr ins and (s) fr the precipitate. FeCl aq Ba OH aq Fe FeCl aq Ba OH aq OH s BaCl aq

6 Chem 11/15 Exam #1 Fall 01 Day Test II. (1 pts) A certain substance cntains nly C, H, and O. Cmbustin f a.50 g sample in excess xygen yields 1.7 g f carbn dixide and 1.1 g f water. Fill in the fllwing table: Element Mles f element in cmpund (pts) Grams f element in cmpund (4 pts) Relative es f element in cmpund* ( pts) C 1.7gCO CO C x x 0.01C g CO 1gC x 0.7g C H 1.1gHO HO H x x 0.14 H g H O 1.008gH x 0.15g H O go O x g g *Use small whle numbers. COH r CHO 4 ( pts) What is the empirical frmula? 4 4

7 Chem 11/15 Exam #1 Fall 01 Day Test III. Three independent questins. (a) (4 pts) The heating rate fr an ven is ᴼC per hur. Initially, the ven is at 56 ᴼF. Hw lng des it take t preheat the ven t 40. ᴼF fr baking a cake? GIVE ANSWER IN MINUTES F 1C hr 60 min fast way : x x x 1.5min F 1000C hr.1 slw way : T 40 / C; T 56 / C f 1.11.C hr 60 min x x 1.5min C hr i (b) (4 pts) Hw many xygen atms are in 10.0 g dinitrgen pentxide (N O 5 )? MM N O x14.0 5x g / gNO5 NO5 6.0x10 ecule NO5 5atm O x x x x x 1 108g ecule N O 10.0gN O N O 6.0x10 ecule N O Methd : g O atms x x x ecules then 5 atms O per ecule gives the abve answer. (c) (4 pts) A cmpund cntains nitrgen, xygen, and sulfur. Analysis f a.0 g sample shws that it cntains g O. Analysis f a.5 g sample shws that it cntains 1.81 g S. What is the empirical frmula f the cmpund? Methd 1--rescale t make bth samples the same size, say g. 1.81gS gsample x 1.04 gs; g N g.5g sample gS x 0.0 S S 1.06g 0.516gO x 0.0 O O 1 16g 0.450gN x 0.0 N 1 N; empirical frmula: NSO 1 14g 5 Methd 0.516gO 1.81gS 0.58 r 5.8% O by mass; r 51.7% S by mass gsample.5gsample The rest is N. Nw use standard technique.