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Chemistry Mid-Term 2006 – Version A

VIEWS: 310 PAGES: 11





          140 points

          2009 – 2010

         MR. CHUBA
(2 points each)

1.   Round 20.589958 to 4, 3, and 2 significant figures, respectively:

     A. 20.59, 20.5, 20
     B. 20.58, 20.5, 20
     C. 20.60, 20.6, 21
     D. 20.59, 20.6, 21

2.   The solution to (22.41 + 0.464) x 999/18.465 is

     A. 1237.32
     B. 1.24 x 103
     C. 1.2 x 104
     D. 1237

3.   The solution to 9.99/22.41 x (18.465 + 0.464) is

     A. 8.44
     B. 8
     C. 8.4
     D. 8.438

4.   At what temperature does 0C = 0.5(0F)?
     A.     C = 60 and 0F = 120
     B.     C = 160 and 0F = 320
     C.     C = 45 and 0F = 90
     D.     C = 0 and 0F = 0

5.    The average daytime temperatures on Earth and Jupiter are 72 0C and 313 K, respectively. Calculate the
     difference in temperature in 0C, between these two planets.

     A. 180C
     B. 72.20C
     C. 19.60C
     D. 1930C

6.   When silicon and oxygen combine to form silicon dioxide, silicon and oxygen

     A. Fuse together to form a new molecule
     B. Retain their identities
     C. Duplicate their mass
     D. Some atoms retain their individual identities and some do not

7.   Which of the following elements has Z = 68 and A = 167?

     A. Erbium
     B. Californium
     C. Calcium
     D. Dysprosium

8.    Aton A has 30 protons, 32 neutrons, and 30 electrons. Atom B has 30 protons, 28 neutrons, and 30 electrons.
      Atoms A and B are

      A. Isotopes
      B. Isobars
      C. Isomers
      D. Isoneutrons

9.    How many electrons and protons, respectively, are there in Ra2+ ?

      A. 88, 88
      B. 86, 88
      C. 224, 226
      D. 228, 224

10. How many electrons does an ion with mass number 210, with 125 neutrons, and a charge of -2 have?

      A. 85
      B. 83
      C. 87
      D. 89

11. The (SO4)2- ion is called

      A. Sulfite ion
      B. Sulfate ion
      C. Sulfur tetroxide ion
      D. Sulfur oxide ion

12. The compound Co2(CO3)3 is named

      A. Cobalt carbonate
      B. Cobalt (III) carbonate
      C. Cobalt (II) carbonate
      D. Cobalt carbon trioxide

13.    A compound in which the nitrite to metal ion ratio is 2:1 has the following formula

      A. M(NO2)2
      B. M(NO2)4
      C. M2NO2
      D. MNO2

14. Which of the following is not a polyatomic ion?

      A. Sulfate
      B. Hydride
      C. Nitrite
      D. Carbonate

15. The name for (BrO3)- is

      A. Bromite ion
      B. Perbromate ion
      C. Bromate ion
      D. Hypobromite ion
16. The oxyacid HIO is named

    A. Hypoiodous acid
    B. Iodic acid
    C. Iodous acid
    D. Periodic acid

17. A certain compound has the name sodium dihydrogen phosphate trihydrate on the bottle. The molecular mass
    (to three significant figures) of this compound is _____ .

    A.   164 g/mol
    B.   120 g/mol
    C.   110 g/mol
    D.   174 g/mol

18. A compound has a formula CaX2. X may be

    A.   Br
    B.   O
    C.   P
    D.   N

19. Using the incorrect name for a compound could be very hazardous in lab. Which of the following compounds
    is followed by its correct name?

    A.   CaF2, calcium fluorite
    B.   Mg(C2H3O2)2 , magnesium acetate
    C.   AlCl3, aluminum trichloride
    D.   FeO, iron (III) oxide

20. Barium chloride is a hydrated salt. A 1.25g sample of the hydrate is heated in an oven until it does not lose
    additional mass. The anhydrous BaCl2 has a mass of 1.06g. What is the formula of the hydrate? The molar
    mass of BaCl2 = 208.2.

    A.   BaCl2∙H2O
    B.   BaCl2∙2 H2O
    C.   BaCl2∙3 H2O
    D.   BaCl2∙5 H2O

21. Atoms of an element, Z, have a ground state electron configuration of 1s 22s22p63s23p1. The element, Z, will
    most likely form a compound with oxygen having the following formula:

    A.   ZO
    B.   ZO2
    C.   Z2O3
    D.   Z3O2

22. The compound that contains 10.4% oxygen is:

    A.   NaOH
    B.   CaO
    C.   Al2O3
    D.   BaO

23. Determine the identity of the element X in the following equation

    C3H6X3 + 3X2 → 3CX2 + 3H2O

    A. O
    B. H
    C. Cl
    D. Br

24. Calculate the molarity when 18.5 g of nitric acid are dissolved in enough water to prepare 100.0 mL of solution.

    A.   2.94 M
    B.   5.78 M
    C.   3.51 M
    D.   0.287 M

25. When 25.0 mL of a 10.6 M HCl solution is diluted to 200.0 mL, what is the final molarity of this acidic

    A.   1.33 M
    B.   2.65 M
    C.   3.98 M
    D.   3.53 M

26. Which of the following compounds do you expect to precipitate in an aqueous solution?

    A.   AgNO3
    B.   PbSO4
    C.   LiBr
    D.   KI

27. The net ionic equation for the precipitation of cobalt (II) nitrate with hydrogen sulfide gas is:

    A.   Co2+ (aq) + S2- (aq) → CoS (s)
    B.   H2S (g) + Co2+ (aq) → CoS (s) + 2 H+ (aq)
    C.   2 Co3+ (aq) + 3 S2- (aq) → Co2S3 (s)
    D.   H2S (aq) + Co2+ (aq) → CoS (s) + 2 H+ (aq)

28. From the following list, the reaction of sodium metal with water is best classified as

    A.   a double-replacement reaction
    B.   a combustion reaction
    C.   a single-replacement reaction
    D.   an oxidation reaction

29. For the reaction below, indicate which elements are reduced and which are oxidized:

2 Cu(NO3)2 (aq) → 2 CuO (aq) + 4 NO2 (aq) + O2 (g)

    Oxidized                    Reduced

    A. nitrogen                 oxygen
    B. copper                   oxygen
    C. copper                   nitrogen
    D. oxygen                   nitrogen
30. In which of the following compounds does manganese have the same oxidation number as it does in KMnO 4 ?

    A.   MnCl2
    B.   MnO2
    C.   Mn2O3
    D.   Mn2O7

31. This model views gases as a group of particles that have no volume or attractive forces. They move rapidly and
collide in elastic collisions. Finally, it defines the nature of temperature.

    A.    atomic theory
    B.    quantum theory
    C.    kinetic molecular theory
    D.    VSEPR theory

32. Decreasing the pressure of a sample of NH3 (g), without changing the temperature, will cause this polar
molecule to behave more like an ideal gas because _____ .

    A.    the molecules hit the wall less frequently
    B.    of Le Chatelier’s principle
    C.    the molecules collide less frequently
    D.    molecules are attracted to one another better

33. For an ideal gas, which of the following quantities will be pressure-dependent?

I. enthalpy
II. entropy
III. free energy

    A.   I only
    B.   II only
    C.   I and II only
    D.   II and III only

34. Which gas would effuse the fastest?

    A. Ne
    B. CO2
    C. Ar
    D. O2

35. Calculate the density, in g/L, of sulfur dioxide gas at 37.0 0C and a pressure of 1440 torr.

    A. 6.0
    B. 0.60
    C. 2.38
    D. 4.76


Solve each of the following problems in this section. Be sure to use the correct number of significant figures
and the correct units in your answers.

( 10 points) 36. Name each of the following:

    a.   PbI2

    b.   Cr(OH)3

    c.   KH2PO4

    d.   Fe(IO4)3

    e.   N 2O 4

    f.   KHCO3

    g.   P4O10

    h.   HIO3

    i.   HBr

    j.   HCN

( 10 points) 37. Write formulas for each of the following compounds:

    a.   Sodium cyanide

    b.   Phosphoric acid

    c.   Uranium (VI) fluoride

    d.   Nitrous acid

    e.   Gold (III) acetate

    f.   Europium (II) bromide

    g.   Osmium (III) phosphate

    h.   Vanadium (IV) sulfite

    i.   Xenon hexafluoride

    j.   Diarsenic trioxide
(2 points) 38. Write the balanced molecular equation for the reaction of aqueous potassium chloride and aqueous
lead nitrate. Indicate the phase of the reactants and products.

(3 points) 39. Write the net ionic equation for the reaction of aqueous sodium chloride and aqueous dimercury (I)
nitrate. Indicate the phase of the reactants and the products.

(3 points) 40. A 45.0 mL sample of 0.300M FeCl3 is reacted with enough NaOH solution to precipitate all the iron
as Fe(OH)3. How many grams of iron (III) hydroxide will be precipitated?

FeCl3 (aq) + 3 NaOH (aq) → Fe(OH)3 (s) + 3 NaCl (aq)

(4 points) 41. Determine the molecular formula of a compound containing 52.63% C, 7.02% H, 12.28% N, and
28.07% O. The molar mass of the molecular formula is 228 g.

41. DDT, an insecticide harmful to fish, birds, and humans is produced by the following reaction:

                                2 C6H5Cl + C2HOCl3 → C14H9Cl5 + H2

In a government lab 1142.0g of chlorobenzene (C6H5Cl) were reacted with 485.0g of chloral (C2HOCl3)

(4 points) Determine the mass of DDT produced.

(2 points) Determine the mass of the excess reactant that remains.

(2 points) If the actual yield of DDT were 200.0g, what was the percent yield?

(5 points) 42. A 0.0600 g piece of magnesium is placed in hydrochloric acid to generate hydrogen gas according to
the equation

Mg (s) + 2 HCl (aq) → MgCl2 (aq) + H2 (g)

The gas is collected in a pneumatic trough at 25.00C. A barometer reading of 755 mm Hg is made during the
experiment. When bubbles of hydrogen cease forming, the bottle is adjusted to the water level in the trough and the
water level is marked on the bottle. Afterwards, the volume of hydrogen gas collected is measured to be 65.0 mL.
The vapor pressure of water at 25.00C is 23.8 mm Hg. Determine the mass, in grams, of hydrogen produced.

(3 points) 43. A sample of carbon dioxide in a 2.50 L flask at 785 torr and 35.0 0C is transferred to a 1.00 L flask at
405 K. Determine the final pressure of the CO2 in atmospheres.
(3 points) 44. A coffee cup calorimeter contains 75.00g of water at 24.000C. A 26.00g sample of a metal is at
85.250C is added. The final temperature of the water and the metal is 28.34 0C. Determine the specific heat of the
metal. The specific heat of water is 4.184 J/g0C

(4 points) 45. Balance the following redox reaction in acidic solution:

             H3AsO4 + Zn → AsH3 + Zn2+

(5 points) 46. Balance the following redox reaction in a basic solution.

             HXeO4- + Pb → Xe + HPbO2-

(4 points) 47. From the following enthalpies of reaction,

CaCO3 (s) → CaO (s) + CO2 (g)                               ∆H = -178.1 kJ/mol

CaO (s) + H2O (l) → Ca(OH)2 (s)                             ∆H = - 65.3 kJ/mol

Ca(OH)2 (s) → Ca2+ (aq) + 2 OH- (aq)                        ∆H = -16.2 kJ/mol

Calculate ∆Hrxn for

Ca2+ (aq) + 2 OH- (aq) + CO2 (g) → CaCO3 (s) + H2O (l)

( 9 points) 48. Using heats of formation data, determine the ∆H rxn for each of the following:

    (a) NH4NO3 (s) → N2O (g) + 2 H2O (l)

    (b) SF6 (g) + 3 H2O (l) → 6 HF (g) + SO3 (g)

    (c) 4 Al (s) + 3 MnO2 (s) → 3 Mn (s) + 2 Al2O3 (s)

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