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Chemistry LibreTexts

Homework 1

  • Page ID
    206864
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    Graded Homework Problems

    Homework 1 in Sapling

     


     

    Problems for Practice

     

    Solutions, hints and answers can be found in the Solutions Page. It is strongly recommended that students do not look at the solutions until after completing or attempting to complete the problems. Going straight to the solutions will reduce the point of the exercises.

    1.1

    Calculate the result of each of the following and record answer with the proper number of significant figures.

    1. 13.4 + 9.8 + 55.99
    2. 340.5 * 419.23
    3. 19.45 / 14.23
    4. 7 - 2.8

    1.2

    Calculate and express the result in the correct number of significant figures.

    1. (1.602 x 10-19 ) x (2.15 x 103)
    2. (3.1667 x 1023 ) x (9.018 x 10-9) / (7.52 x 104)
    3. 1.714 x 10-1 + 1.96 x 10-3 + 1.255 x 10-2
    4. (7.00743 - 7.00521) / (5.9831 x 1019 )
    5. (4.832 x 10-5 - 4.760 x 10-5) / (4.832 x 10-5) x 100 (100 is exact)
    6. (9.02 x 103 + 8.99 x 103 + 1.065 x 104) / 3 (3 is exact)

    1.3

    Convert the following temperatures to Kelvin and Fahrenheit degrees.

    1. room temperature: 20.0 oC
    2. the boiling point of water: 100.oC
    3. the temperature of human: 37.0 oC

    1.4

    Using the following table, calculate the volume of 50.0 g of each of the following substances at 20.0o C. What does the volume of oxygen gas tell you about the properties of gasses?

    Substance

    Physical State

    Density (g/cm3)

    Ethanol

    Liquid

    0.789

    Iron

    Solid

    7.87

    Oxygen

    Gas

    0.00133

    1.5

    A student gets three thermometers from the lab. He notices that these thermometers use different units for measurements. They are oF, oC, and K. If he puts these thermometers into three water baths and observe a 10 degree change for each thermometer, which water bath has the smallest change in temperature ?

    1.6

    What is the main difference between each of the following pairs?

    1. An elemental substance (element) and a compound
    2. Physical and chemical changes
    3. Homogeneous and heterogeneous mixtures

    1.7

    Define whether each of the following is a pure substance or a mixture.

    1. salad dressing
    2. copper
    3. bronze
    4. silk
    5. ice
    6. sand
    7. magnesium
    8. solid potassium iodide (KI)
    9. honey

    1.8

    Are these chemical or physical changes?

    1. A nail rusting.
    2. Toast burning.
    3. Water boiling.
    4. Ice cream melting.

    1.9

    The actual amount of magnesium in a sample is 21.14%. A student analyzed the magnesium in the sample and obtained the results: 20.36%, 20.37%, 20.34%, 20.37%. Explain the accuracy and precision of these results.

     

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