Exercises

Part 1

  1. Why do we use an object’s mass, rather than its weight, to indicate the amount of matter it contains?
  2. What properties distinguish solids from liquids? Liquids from gases? Solids from gases?
  3. How does a heterogeneous mixture differ from a homogeneous mixture? How are they similar?
  4. How does a homogeneous mixture differ from a pure substance? How are they similar?
  5. How do molecules of elements and molecules of compounds differ? In what ways are they similar
  6. How does an atom differ from a molecule? In what ways are they similar?
  7. Many of the items you purchase are mixtures of pure compounds. Select three of these commercial products and prepare a list of the ingredients that are pure compounds.
  8. Classify each of the following as an element, a compound, or a mixture:
    1. copper
    2. water
    3. nitrogen
    4. sulfur
    5. air
    6. sucrose
    7. a substance composed of molecules each of which contains two iodine atoms
    8. gasoline
  9. A sulfur atom and a sulfur molecule are not identical. What is the difference?
  10. How are the molecules in oxygen gas, the molecules in hydrogen gas, and water molecules similar? How do they differ?
  11. We refer to astronauts in space as weightless, but not without mass. Why?
  12. As we drive an automobile, we don’t think about the chemicals consumed and produced. Prepare a list of the principal chemicals consumed and produced during the operation of an automobile.
  13. Matter is everywhere around us. Make a list by name of fifteen different kinds of matter that you encounter every day. Your list should include (and label at least one example of each) the following: a solid, a liquid, a gas, an element, a compound, a homogenous mixture, a heterogeneous mixture, and a pure substance.
  14. When elemental iron corrodes it combines with oxygen in the air to ultimately form red brown iron(III) oxide which we call rust.
    1. If a shiny iron nail with an initial mass of 23.2 g is weighed after being coated in a layer of rust, would you expect the mass to have increased, decreased, or remained the same? Explain.
    2. If the mass of the iron nail increases to 24.1 g, what mass of oxygen combined with the iron?
  15. As stated in the text, convincing examples that demonstrate the law of conservation of matter outside of the laboratory are few and far between. Indicate whether the mass would increase, decrease, or stay the same for the following scenarios where chemical reactions take place:
    1. Exactly one pound of bread dough is placed in a baking tin. The dough is cooked in an oven at 350 °F releasing a wonderful aroma of freshly baked bread during the cooking process. Is the mass of the baked loaf less than, greater than, or the same as the one pound of original dough? Explain.
    2. When magnesium burns in air a white flaky ash of magnesium oxide is produced. Is the mass of magnesium oxide less than, greater than, or the same as the original piece of magnesium? Explain.
    3. Antoine Lavoisier, the French scientist credited with first stating the law of conservation of matter, heated a mixture of tin and air in a sealed flask to produce tin oxide. Did the mass of the sealed flask and contents decrease, increase, or remain the same after the heating?

Part 2

  1. Classify each of the following changes as physical or chemical:
    1. condensation of steam
    2. burning of gasoline
    3. souring of milk
    4. dissolving of sugar in water
    5. melting of gold
  2. Classify each of the following changes as physical or chemical:
    1. coal burning
    2. ice melting
    3. mixing chocolate syrup with milk
    4. explosion of a firecracker
    5. magnetizing of a screwdriver
  3. The volume of a sample of oxygen gas changed from 10 mL to 11 mL as the temperature changed. Is this a chemical or physical change?
  4. A 2.0-liter volume of hydrogen gas combined with 1.0 liter of oxygen gas to produce 2.0 liters of water vapor. Does oxygen undergo a chemical or physical change?
  5. Explain the difference between extensive properties and intensive properties.
  6. Identify the following properties as either extensive or intensive.
    1. volume
    2. temperature
    3. humidity
    4. heat
    5. boiling point
  7. The density (d) of a substance is an intensive property that is defined as the ratio of its mass (m) to its volume (V).[latex]\text{density}=\frac{\text{mass}}{\text{volume}}[/latex]; [latex]\text{d}=\frac{\text{m}}{\text{V}}[/latex]. Considering that mass and volume are both extensive properties, explain why their ratio, density, is intensive.

Part 3

  1. Using the periodic table, classify each of the following elements as a metal or a nonmetal, and then further classify each as a main-group (representative) element, transition metal, or inner transition metal:
    1. cobalt
    2. europium
    3. iodine
    4. indium
    5. lithium
    6. oxygen
    7. cadmium
    8. terbium
    9. rhenium
  2. Use the periodic table to give the name and symbol for each of the following elements:
    1. the halogen in the same period as the alkali metal with 11 protons
    2. the alkaline earth metal in the same period with the neutral noble gas with 18 electrons
    3. the noble gas in the same row as an isotope with 30 neutrons and 25 protons
    4. the noble gas in the same period as gold
  3. Write a symbol for each of the following neutral isotopes. Include the atomic number and mass number for each.
    1. the alkali metal with 11 protons and a mass number of 23
    2. the noble gas element with and 75 neutrons in its nucleus and 54 electrons in the neutral atom
    3. the isotope with 33 protons and 40 neutrons in its nucleus
    4. the alkaline earth metal with 88 electrons and 138 neutrons
  4. Write a symbol for each of the following neutral isotopes. Include the atomic number and mass number for each.
    1. the chalcogen with a mass number of 125
    2. the halogen whose longest-lived isotope is radioactive
    3. the noble gas, used in lighting, with 10 electrons and 10 neutrons
    4. the lightest alkali metal with three neutrons
  5. Give the number of protons, electrons, and neutrons in neutral atoms of each of the following isotopes:
    1. [latex]{}_{3}^{7}\text{Li}[/latex]
    2. [latex]{}_{52}^{125}\text{Te}[/latex]
    3. [latex]{}_{47}^{109}\text{Ag}[/latex]
    4. [latex]{}_{7}^{15}\text{N}[/latex]
    5. [latex]{}_{15}^{31}\text{P}[/latex]
  6. Using the periodic table, predict whether the following compounds are ionic or covalent:
    1. SO2
    2. CaF2
    3. N2H4
    4. Al2(SO4)3