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2.E: Matter and Energy (Exercises)

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    2.1-2.3 Matter and Changes

    1. Match the following terms with their meaning.
      Terms Definitions
      (a) Mass a. a measure of the total quantity of matter in an object
      (b) Volume b. a measure of how strongly gravity pulls on an object
      (c) Weight c. a measure of the space occupied by an object
    2. Identify each as either matter or not matter.
    • a book
    • hate
    • light
    • a car
    • a fried egg

    3. Give an example of matter in each phase: solid, liquid, or gas.

    4. Does each statement represent a physical property or a chemical property?

    • Sulfur is yellow.
    • Steel wool burns when ignited by a flame.
    • A gallon of milk weighs over eight pounds.

    5. Does each statement represent a physical property or a chemical property?

    • A pile of leaves slowly rots in the backyard.
    • In the presence of oxygen, hydrogen can interact to make water.
    • Gold can be stretched into very thin wires.

    6. Does each statement represent a physical change or a chemical change?

    • Water boils and becomes steam.
    • Food is converted into usable form by the digestive system.
    • The alcohol in many thermometers freezes at about −40 degrees Fahrenheit.

    7. Does each statement represent a physical change or a chemical change?

    • Graphite, a form of elemental carbon, can be turned into diamond, another form of carbon, at very high temperatures and pressures.
    • The house across the street has been painted a new color.
    • The elements sodium and chlorine come together to make a new substance called sodium chloride.

    8. Distinguish between an element and a compound. About how many of each are known?

    9. What is the difference between a homogeneous mixture and a heterogeneous mixture?

    10. Identify each as a heterogeneous mixture or a homogeneous mixture.

    • Salt is mixed with pepper.
    • Sugar is dissolved in water.
    • Pasta is cooked in boiling water.

    11. Identify each as a heterogeneous mixture or a homogeneous mixture.

    • air
    • dirt
    • a television set

    Answers

      1. matter
      2. not matter
      3. not matter
      4. matter
      5. matter

    8. An element is a fundamental chemical part of a substance; there are about 115 known elements. A compound is a combination of elements that acts as a different substance ; there are over 50 million known substances.

      1. homogeneous
      2. heterogeneous
      3. heterogeneous

    2.4 Density

    0. Give at least three possible units for density.

    1. What are the units when density is inverted? Give three examples.
    2. A sample of iron has a volume of 48.2 cm3. What is its mass?
    3. A sample of air has a volume of 1,015 mL. What is its mass?
    4. The volume of hydrogen used by the Hindenburg, the German airship that exploded in New Jersey in 1937, was 2.000 × 108 L. If hydrogen gas has a

      density of 0.0899 g/L, what mass of hydrogen was used by the airship?

    5. The volume of an Olympic-sized swimming pool is 2.50 × 109 cm3. If the pool is filled with alcohol (d = 0.789 g/cm3), what mass of alcohol is in the pool?
    6. A typical engagement ring has 0.77 cm3 of gold. What mass of gold is present?
    7. A typical mercury thermometer has 0.039 mL of mercury in it. What mass of mercury is in the thermometer?
    8. What is the volume of 100.0 g of lead if lead has a density of 11.34 g/cm3?
    9. What is the volume of 255.0 g of uranium if uranium has a density of 19.05 g/cm3?
    10. What is the volume in liters of 222 g of neon if neon has a density of 0.900 g/L?
    11. What is the volume in liters of 20.5 g of sulfur hexafluoride if sulfur hexafluoride has a density of 6.164 g/L?
    12. Which has the greater volume, 100.0 g of iron (d = 7.87 g/cm3) or 75.0 g of gold (d = 19.3 g/cm3)?
    13. Which has the greater volume, 100.0 g of hydrogen gas (d = 0.0000899 g/cm3) or 25.0 g of argon gas (d = 0.00178 g/cm3)?

    Answers:

    0. g/mL, g/L, and kg/L (answers will vary)

    1.  
    2. 379 g
    3.  
    4. 1.80 × 107 g
    5.  
    6. 15 g
    7.  
    8. 8.818 cm3
    9.  
    10. 247 L
    11.  
    12. The 100.0 g of iron has the greater volume

    2.5 Temperature 

    1. Perform the following conversions.

    255°F to degrees Celsius

    −255°F to degrees Celsius

    50.0°C to degrees Fahrenheit

    −50.0°C to degrees Fahrenheit

    2. Perform the following conversions.

    1,065°C to degrees Fahrenheit

    −222°C to degrees Fahrenheit

    400.0°F to degrees Celsius

    200.0°F to degrees Celsius

    3. Perform the following conversions.

    100.0°C to kelvins

    −100.0°C to kelvins

    100 K to degrees Celsius

    300 K to degrees Celsius

    4. Perform the following conversions.

    1,000.0 K to degreesCelsius

    50.0 K to degrees Celsius

    37.0°C to kelvins

    −37.0°C to kelvins

    Convert 0 K to degreesCelsius. What is the significance of the temperature in

    degrees Celsius?

    Convert 0 K to degreesFahrenheit. What is the significance of the temperature in degreesFahrenheit?

    5. The hottest temperature ever recorded on the surface of the earth was 136°F in Libya in 1922. What is the temperature in degrees Celsius and in kelvins?

    6. The coldest temperature ever recorded on the surface of the earth was −128.6°F in Vostok, Antarctica, in 1983. What is the temperature in

    degrees Celsius and in kelvins?

     

    Answers

    1. 124°C
    2. −159°C
    3. 122°F
    4. −58°F
    5.  
      1. 373 K
      2. 173 K
      3. −173°C
      4. 27°C
    7.  
    8. −273°C. This is the lowest possible temperature in

      degrees

      Celsius.
    9.  
    10. 57.8°C; 331 K
    11.  

    2.6 Energy and Heat Capacities.

    Note: you will need to consult a table of heat capacities, such as the one included here, in order to solve many of these problems.

     0. A pot of water is set on a hot burner of a stove. What is the direction of heat flow?

    1. Some uncooked macaroni is added to a pot of boiling water. What is the direction of heat flow?

    2. How much energy in calories is required to heat 150 g of H2O from 0°C to 100°C?

    3. How much energy in calories is required to heat 125 g of Fe from 25°C to 150°C?

    4. If 250 cal of heat were added to 43.8 g of Al at 22.5°C, what is the final temperature of the aluminum?

    5. If 195 cal of heat were added to 33.2 g of Hg at 56.2°C, what is the final temperature of the mercury?

    6. A sample of copper absorbs 145 cal of energy, and its temperature rises from 37.8°C to 41.7°C. What is the mass of the copper?

    7. A large, single crystal of sodium chloride absorbs 98.0 cal of heat. If its temperature rises from 22.0°C to 29.7°C, what is the mass of the NaCl crystal?

    8. If 1.00 g of each substance in this Table  were to absorb 100 cal of heat, which substance would experience the largest temperature change?

    9. If 1.00 g of each substance in this Table were to absorb 100 cal of heat, which substance would experience the smallest temperature change?

    10. Determine the heat capacity of a substance if 23.6 g of the substance gives off 199 cal of heat when its temperature changes from 37.9°C to 20.9°C.

    11. What is the heat capacity of gold if a 250 g sample needs 133 cal of energy to increase its temperature from 23.0°C to 40.1°C?

    Answers

    Edit section

    1. Heat flows into the pot of water.

    1. 15,000 cal

    1. 49.0°C

    1. 404 g

    1. glass would experience the largest temperature change.

    1. 0.496 cal/g•°C

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