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2.E: Homework Chapter 2

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    208484
  • 1) You ask a classmate how much homework your chemistry professor assigned. Your classmate answers, “twenty.” Is that a proper answer? Why or why not?

    2) Define significant figures. Why are they important?

    3) Define the different types of zeros found in a number and explain whether or not they are significant.

    4) Give the two conversion factors you can construct using each pair of units.

    1. meters and kilometers
    2. liters and microliters
    3. seconds and milliseconds

    5) In general, how can you identify whether or not you have written the correct conversion factor for the problem?

    6) Construct a conversion factor that can convert from one unit to the other in each pair of units.

    1. meter to km
    2. inch to cm
    3. pounds to kilogram

    Scientific Notation

    7) Convert each number into scientific notation.

    1. 100,000,000
    2. 0.0004970
    3. 30.01
    4. 2500

    8) Convert each number into scientific notation.

    1. 304,300,000
    2. 0.0004
    3. 1000.
    4. 0.345

    9) Convert each number into scientific notation.

    1. 736,350
    2. 0.0042
    3. 2500
    4. 0.478

    10) Convert each number into decimal notation.

    1. 7.42 x 103
    2. 1.3 x 10-3
    3. 1.5 x 106
    4. 1.5147 x 10‑5

    11) Convert each number into decimal notation.

    1. 8.62 x 104
    2. 5.5 x 10-3
    3. 1.02 x 10-6
    4. 6.03 x 10-10

    12) Convert each number into decimal notation.

    1. 8.35 x 106
    2. 6.3 x 10-4
    3. 1.8 x 106
    4. 7.24 x 10-6

    13) Fill in the blanks.

      Scientific Notation Decimal Notation  
    a) 4.7 x103  
    b)   7,410.
    c) 9.3 x 10-4  
    d)   0.0045

    14) Fill in the blanks.

      Scientific Notation Decimal Notation
    a) 5.36 x106  
    b)   1,120.0
    c) 1.3 x 10-2  
    d)   0.010

     15) Fill in the blanks.

      Scientific Notation Decimal Notation
    a) 8.4 x 105  
    b)   513
    c) 6.30 x 10-6  
    d)   0.250

    Significant Figures

    16. Use each diagram to report a measurement to the proper number of significant figures.

    clipboard_e33288cfd897d36148e584306f1bc31bd.png

    clipboard_e58cfdd853870eb0f83638a25731365fa.png

    17) Use each diagram to report a measurement to the proper number of significant figures.

    clipboard_e8788e93d890786df509b01050dd40de0.png

    clipboard_e1657acf3b5f66a2ded1d8bcbcba70a9c.png

    18) Use each diagram to report a measurement to the proper number of significant figures.

    clipboard_e63b741842977c8e15090e1442933a56c.png

    clipboard_ed74d637f63aa438f42a54a8b048fe332.png

    19) Give the number of significant figures in each. Identify the rule for each.

    1. 0.000140500 s
    2. 630,001 kg
    3. 155.000 in
    4. 0.0745 m

    20) Give the number of significant figures in each. Identify the rule for each.

    1. 0.000250600 s
    2. 720,055 kg
    3. 589.560 in
    4. 0.0856 m

    21) Give the number of significant figures in each. Identify the rule for each.

    1. 0.00540500 s
    2. 890,024 kg
    3. 729.770 in
    4. 0.0961 m

    22) How many significant figures are in each number?

    1. 1.05
    2. 9,500
    3. 0.0004505
    4. 7563

    23) How many significant figures are in each number?

    1. 0.00045050
    2. 7.210 × 106
    3. 5.005 × 10−6
    4. 4861

    24) How many significant figures are in each number?

    1. 0.052010
    2. 0.3940
    3. 8200
    4. 8563

    Rounding

    25) Round each number to three significant figures.

    1. 24.632
    2. 0.34244
    3. 43,539
    4. 6.9978 x 106

    26) Round each number to three significant figures.

    1. 35.743
    2. 0.45355
    3. 54640
    4. 7.0089 x 106

    27) Round each number to three significant figures.

    1. 56.45
    2. 8.90443 × 108
    3. 1,000,000
    4. 0.9841

    28) Determine if each number is rounded correctly to three significant figures. For any items that are incorrect, correct them.

    1. 3.459 x 103 to 3.5 x 103
    2. 4.874 x 103 to 50
    3. 87.42 to 87.4
    4. 0.09853 to 0.010

    29) Determine if each number is rounded correctly to three significant figures. For any items that are incorrect, correct them.

    1. 4.560 x 103 to 4.5 x 103
    2. 8.514 x 103 to 85
    3. 93.72 to 93.7
    4. 0.05312 to 0.053

    30) Determine if each number is rounded correctly to three significant figures. For any items that are incorrect, correct them.

    1. 5.670 x 103 to 5.7 x 103
    2. 5.783 x 103 to 60
    3. 87.42 to 87.4
    4. 0.023541 to 0.024

    31) Complete the table.

    Number Rounded to 4 Significant Figures Rounded to 2 Significant Figures Rounded to 1 Significant Figure
    a. 53.53229 53.53 54 5 x 101
    b.216.3535      
    c. 0.36682      
    d. 0.00888881      

    32) Complete the table.

    Number Rounded to 4 Significant Figures Rounded to 2 Significant Figures Rounded to 1 Significant Figure
    a. 64.64320 64.64 64 6 x 101
    b.335.4545      
    c. 0.54156      
    d. 0.00777772      

    33) Complete the table.

    Number Rounded to 4 Significant Figures Rounded to 2 Significant Figures Rounded to 1 Significant Figure
    a. 82.6268 82.63 83 8 x 101
    b.654.8545      
    c. 0.75126      
    d. 0.00777774      

    Significant Figures in Calculations

    34) Determine if each calculation has the correct number of significant figures. For any items that are incorrect, correct them.

    1. 45.3254 x 59.00205 = 2674.3
    2. 0.00830 x 47.351 = 0.039
    3. 0.008070 / 5018.3 = 1.61811 x 10-6
    4. 0.04541 x 7143.5 = 324.39

    35) Determine if each calculation has the correct number of significant figures. For any items that are incorrect, correct them.

    1. 105.34 x 47.334532 = 4986.22
    2. 0.047 x 23.3544 = 1.098
    3. 5.5225 / 503.455 = 0.010969
    4. 0.000154*1002.2 = 0.15

    36) Determine if each calculation has the correct number of significant figures. For any items that are incorrect, correct them.

    1. 17.354 x 875.214 = 15100
    2. 0.0035 x 20.0456 = 0.07
    3. 0.00486 / 40.8954 = 0.000119
    4. 0.00225 * 2458.3 = 5.53

    37) Determine if each calculation has the correct number of significant figures. For any items that are incorrect, correct them.

    1. 5.8 + 63.09 – 14 = 54.9
    2. 4301 – 2900.14 + 1.6 = 1402
    3. 0.00354 + 0.86 = 0.863
    4. 0.00974 – 0.008 = 0.00074

    38) Determine if each calculation has the correct number of significant figures. For any items that are incorrect, correct them.

    1. 7.4 + 73.07 – 24 = 56.5
    2. 5323 – 3914.24 + 0.7 = 1409
    3. 0.00725 + 0.35 = 0.357
    4. 0.00653 – 0.003 = 0.00353

    39) Determine if each calculation has the correct number of significant figures. For any items that are incorrect, correct them.

    1. 3.5 + 94.04 – 50 = 47.5
    2. 8206 – 5614.25 + 5.5 = 2597.25
    3. 0.00354 + 0.864 = 0.868
    4. 0.01874 – 0.010 = 0.00874

    40) Determine if each calculation has the correct number of significant figures. For any items that are incorrect, correct them.

    1. (9.95 + 3.09) / 7.40000 = 1.762
    2. (1045.3 – 1.4) x 1.604 = 1674
    3. (749.40 + 6.7) / 4.54 = 1.6 x 102
    4. (845 / 301457) + 5.000198 = 5.00

    41) Determine if each calculation has the correct number of significant figures. For any items that are incorrect, correct them.

    1. (8.65 + 2.85) / 8.96000 = 1.283
    2. (2252.5 – 2.8) x 2.765 = 6220
    3. (760.55 + 8.8) / 5.64 = 1.4 x 102
    4. (945 / 54147) + 4.51400014 = 4.53

    42) Determine if each calculation has the correct number of significant figures. For any items that are incorrect, correct them.

    1. (1.24 + 3.14) / 4.54000 = 0.96
    2. (3251 – 3.6) x 6.54 = 21238
    3. (651.25 + 6.3) / 6.55 = 100
    4. (360 /64025) + 5.4100087 = 5.41

    Unit Conversion

    43) Convert the following metric quantities into the indicated units. Identify the number of significant figures in each answer.

    1. 1000. g into milligrams
    2. 6981 nm into meters
    3. 15 mL into liters
    4. 345 cm to millimeters

    44) Convert the following metric quantities into the indicated units. Identify the number of significant figures in each answer.

    1. 8541 g into mg
    2. 7896 nm into m
    3. 25 kL into L
    4. 62 cm to mm

    45) Convert the following metric quantities into the indicated units. Identify the number of significant figures in each answer.

    1. 34 kg to g
    2. 7539.34 nm to km
    3. 36 L into cL
    4. 109 cm to mm

    46) Use English-to-Metric and Metric-to-English conversion factors to calculate the following:

    1. 87.6 ft into centimeters
    2. 557 yd to meters
    3. 645 feet to centimeters
    4. 7.0 inch to centimeters

    47) Use English-to-Metric and Metric-to-English conversion factors to calculate the following:

    1. 90.7 ft into mm
    2. 14.8 lb to kg
    3. 400. m to mi
    4. 12.0 in to cm

    48) Use English-to-Metric and Metric-to-English conversion factors to calculate the following:

    1. 71.3 ft to mm
    2. 15.2 lbs to kg
    3. 520. m to mi
    4. 8.0 in to cm

    49) Fill in the blank to complete the table.

    m km mm nm pm
    6.02 x10-5 m   6.02 x 10-2 mm    
            25.3 pm
          225 nm  
      8.22 x 10-3 km      
        4.2 x 105 mm    

    50) Fill in the blank to complete the table.

    m km mm nm pm
    5.36 x10-5 m   5.36 x 10-2 mm    
            18.7 pm
          345 nm  
      6.33 x 10-3 km      
        5.5 x 105 mm    

    51) Fill in the blank to complete the table.

    m km mm nm pm
    1.88 x10-5 m   1.88 x 10-2 mm    
            14.3 pm
          365 nm  
      6.34 x 10-3 km      
        6.9 x 105 mm    

    Unit Raised to a Power

    52) Perform each conversion.

    1. 1.2 ft2 = _____in2
    2. 1.2 yd2 = _______ft2
    3. 1.2 m3 = _______ yd3

    53) Perform each conversion.

    1. 2.4 ft2 = _____in2
    2. 2.4 yd2 = _______ft2
    3. 2.4 m3 = _______ yd3

    54) Perform each conversion.

    1. 3.5 ft2 = _____in2
    2. 3.5 yd2 = _______ft2
    3. 35 m3 = _______ yd3

    55) A pizza has an area of 3.44 m2. Convert the pizza’s area to each of the following units.

    1. in2
    2. mm2
    3. km2

    56) A pizza has an area of 2.50 m2. Convert the pizza’s area to each of the following units.

    1. in2
    2. mm2
    3. km2

    57) A pizza has an area of 13.5 m2. Convert the pizza’s area to each of the following units.

    1. in2
    2. mm2
    3. km2

    Density

    58) A copper strip has a mass of 4.67 g and a volume of 0.523 cm3. What is the density of the copper strip? Is the strip pure copper?

    59) A lead strip has a mass of 7.41 g and a volume of 0.654 cm3. What is the density of the lead strip? Is the strip pure lead?

    60) A silver ingot has a mass of 70.34 g and a volume of 8.5 cm3. What is the density of the ingot? Is the ingot pure silver?

    61) Given that the density of gold is 19.3 g/cm3,

    1. Determine the mass of gold (in grams) in an ingot with a volume of 121 cm3.
    2. Determine the volume of gold (in cm3) in an ingot with a mass of 1354 g.

    62) Given that the density of Cu is 8.93 g/cm3,

    1. Determine the mass of copper (in grams) in a copper strip with a volume of 433.0 cm3.
    2. Determine the volume of copper (in cm3) in a copper strip with a mass of 502.34 grams.

    63) Given that the density of lead is 11.34 g/cm3,

    1. Determine the mass of lead (in grams) in a lead block with a volume of 607.9 cm3.
    2. Determine the volume of lead (in cm3) in a lead block with a mass of 802.35 grams.

    Cumulative Problems

    64) If the walls in a room are 955 square feet in area, and a gallon of paint covers 15 square yards, how many gallons of paint are needed to paint the walls in the room? (3 ft = 1 yd)

    65) Gas is sold for $1.399 per liter in Toronto, Canada. Your car needs 12.00 gallons. How much will your credit card be charged in Canadian dollars (minus tax)?

    66) If an object has a density of 8.65 g/cm3, what is its density in units of kg/m3?

    67) Water is being pumped out of a reservoir at a rate of 2.54 liters per 15.0 seconds. If the reservoir contains 1.0500 x 106 gallons of water, how many hours will it take to empty it?

    68) The mass of an average blueberry is 0.75 g and the mass of an automobile is 2,010.3 kg. Find the number of automobiles whose total mass is the same as 1.0 x 1010 blueberries?

    69) Tom and Mary both have farms. Tom raises chickens for eggs while Mary plants apples. 3.00 lb of apples can be exchanged with 1 dozen eggs. If Tom has 130. eggs to exchange with Mary, how many pounds of apples will he get?

    70) Calculate the number of seconds in 1.00 year.

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