Chemcom Unit 3 Exam . . . Materials: Structures and Uses

 

True/False (Choose the best answer.)

  1. A nail rusting is an example of a physical change.


  2. Chemical changes result in the production of a new substance.


  3. Metals are generally found in the right-hand side of the periodic table.


  4. An element that can be crushed easily with a hammer is most likely a metal.


  5. The symbols for elements always start with a capital letter.


  6. When first constructing the periodic table, Mendeleev arranged the elements from lowest to highest atomic mass.


  7. Mendeleev arranged the periodic table so that elements with similar chemical properties were in the same column.


  8. Silicon (Si) has a boiling point of 3267 oC and Tin (Sn) has a melting point of 2603 oC. A good guess for the melting point of Germanium (Ge) would be 5870 oC.


  9. The earth is divided into three main layers: the atmosphere, the hydrosphere, and the lithosphere.


  10. Most of the earth's elements are found in the lithosphere.


  11. Ores that are mined generally contain metals that are negative ions.


  12. In the Converting Copper Lab, the copper gained mass while it was heated.


  13. Precious metals (Copper, Silver, Gold, etc.) tend to be very reactive.


  14. The term reduction refers to the gain of electrons.


  15. The reaction, Cu 2+ + 2e - Cu, is an oxidation reaction.


  16. The Law of Conservation of Matter states, "Matter cannot be created or destroyed."


  17. In the reaction, 2 CO + O 2 2 CO 2 , involves 8 oxygen atoms.


  18. In the reaction, 2 CO + O 2 2 CO 2 , is balanced.


  19. One mole = 6.02 x 10 23.


  20. One mole of H2 has a mass of 2 g. (You will have to refer to a periodic table to answer this question.)


  21. The percentage of carbon (C) in carbon monoxide (CO) is 43 %. (You will have to refer to a periodic table to answer this question.)


  22. Petroleum in considered a renewable resource.


  23. Plastic accounts for the most waste generated in the United States both before and after recycling.


  24. Two forms of carbon are graphite and diamond. These different forms are defined as allotropes.


  25. Brass, bronze, and steel are all examples of alloys.


Multiple Choice (Choose the best answer.)

  1. In the Metal or Nonmetal Lab, you performed tests on several metals. Which test(s) below used chemical properties?

    I. ConductivityII. Acid TestIII Adding CuCl 2IV. Crushing with a Hammer

    I only

    II only

    II and III only

    I, II, III and IV

  2. Where are metals found on the periodic table?

    On the left-hand side.

    On the right-and side.

    On the bottom.

    On the top.


    Use the Periodic Table to answer questions 3 - 9 below:

  3. Of the elements tested in the Metal or Nonmetal Lab, which was a metalloid?

    Silicon (Si)

    Sulfur (S)

    Lithium (Li)

    Helium (He)

  4. Magnesium forms MgCl 2 and Silicon forms SiCl 4 when combined with Chlorine. What will be the formula when Aluminum combines with Chlorine?

    AlCl

    AlCl 2

    AlCl 3

    AlCl 4

  5. Given the information in problem 4, what would be the likely formula when beryllium combines with chlorine?

    BeCl

    BeCl 2

    BeCl 3

    BeCl 4

  6. The boiling temperature of Helium (He) is 4.2 K and the boiling temperature of Argon (Ar) is 87.3 K. What is the most reasonable guess for the boiling point of Ne?

    2.4 K

    91.5 K

    84.9 K

    43.7 K

  7. The atomic weight of Carbon (C) is 12 g/mole and the atomic weight of Oxygen (O) is 16 g/mol. What is the best guess for the atomic weight of Nitrogen (N)?

    4 g/mol

    14 g/mol

    20 g/mol

    28 g/mol

  8. Which elements fall in the same family or group?

    C, N, and O

    H, Be, and Al

    He, Ne, and Ar

    He, F, and S

  9. Which elements fall in the same period?

    C, N, and O

    H, Be, and Al

    He, Ne, and Ar

    He, F, and S

  10. You are most likely to find oxygen gas, O 2 in earth's _____.

    Atmosphere

    Hydrosphere

    Lithosphere

    Core

  11. Metals are distriuted _____ throught the countries on earth and are _____ .

    evenly . . . recyclable

    evenly . . . renewable

    unevenly . . . recyclable

    unevenly . . . renewable

  12. In the Converting Copper Lab, copper was heated, turned black, and increased its mass. The most likely explanation for this is that _____.

    Copper atoms were changed to some other metal.

    Copper atoms reacted with the crucible.

    Copper atoms reacted with oxygen to form copper oxide.

    Copper atoms reacted with heat to expand.


    Use this table to answer questions 13 and 14.

  13. Does a reaction occur when sodium metal is place in a solution of Pb 2+?

    Yes

    No

    Not enough information is given.

  14. Which metal is the most reactive?

    Mg

    Na

    Pb

    It is impossible to tell.

  15. A neutral sodium (Na) has 11 protons. How many electrons does a Na atom have?

    10

    11

    12

    It is impossible to tell.

  16. A chlorine ion (Cl -1) has 17 protons. How many electrons does it have?

    16

    17

    18

    It is impossible to tell.

  17. A magnesium ion (Mg 2+ ) has 10 electrons. How many protons does it have?

    8

    10

    12

    It is impossible to tell.

  18. The reaction Zn Zn 2+ + 2 e - is a(n) _____.

    reduction reaction because it is gaining electrons

    reduction reaction because it is losing electrons

    oxidation reacton because it is gaining electrons

    oxidation reaction because it is losing electrons

    In the Metal Reactivities Lab you observed the following reaction:

    2 Ag + + Zn Zn 2+ + 2 Ag

    Use this reaction to answer questions 19 and 20 below.

  19. The Ag + ion is being _____ while the Zn atom is being _____.

    oxidized . . . reduced

    oxidized . . . oxidized

    reduced . . . oxidized

    reduced . . . reduced

  20. Which reaction below indicates what is happening to the Ag + ion?

    Ag + + e - Ag

    Ag + e - Ag +

    Ag Ag + + e -

    Ag Ag + + e -

    Questions 21 - 23 refer to the diagram below.

  21. Which reaction best represents the diagram?

    H + Br + Mg 2 H + 2 Br + Mg

    HBr + Mg 2 H + Mg + 2 Br

    HBrMg H 2 + MgBr 2

    HBr + Mg H 2 + MgBr 2

  22. The reaction shown in the diagram is not balanced because ______.

    The hydrogen atoms aren't balanced.

    The bromine atoms aren't balanced.

    The magnesium atoms aren't balanced.

    Both A and B.

  23. Which below shows a balanced reaction?

    HBr + Mg H 2 + MgBr 2

    2 HBr + Mg H 2 + MgBr 2

    HBr + Mg 2 H 2 + MgBr 2

    HBr + 2 Mg H 2 + MgBr 2

  24. Heating lead sulfide in air gives the reaction ___ PbS + ___ O 2 ___ PbO + ___ SO 2 . What would the coefficients have to be for the reaction to be balanced?

    1, 1, 1, 1

    2, 1, 2, 2

    2, 3, 2, 2

    1, 1, 2, 2

  25. One mole of an element equals _____.

    6.02 x 10 23 atoms

    the mass of the element as found on the periodic table

    neither A nor B

    both A and B

    Use the periodic table below to answer questions 25 and 26.

  26. What is the mass of 6.02 x 10 23 Na 2 O molecules?

    23 g

    39 g

    62 g

    78 g

  27. What is the percent of Li in LiF?

    6.9 %

    26 %

    31 %

    27 %

  28. The profitability for mining a certain location depends upon _____.

    the abundance of the metal in the ore

    the price of the metal in the world market

    the cost to refine the metal

    All of the above.

  29. Aluminum is more easily produced from recycled aluminum cans than from aluminum containing minerals because _____.

    recycling aluminum avoids the costs of mining and processing the ore

    recycling aluminum does not require the use of dangerous chemicals

    recycling aluminum does not involve any processing costs

    all of the above

  30. The surfaces of metals can be modified by _____.

    applying different coatings

    plating the surace with different metals

    coating the surface with plastic films

    all of the above.

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