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Chemistry LibreTexts

Homework 37

  • Page ID
    28952
  • 2.15

    A Nickel is measured using a ruler with markings at every 0.1 mm. What is the correct measurement report for the Nickel?

    What We Know: According to the US government, the size of a Nickel is 0.835 inches or 21.21 mm

    What It's Asking For: Using significant figures, determine the correct measurement of the Nickel.

    Strategy: Every digit in a scientific measurement is certain except for the last digit. Unless stated otherwise, the last digit is estimated with an uncertainty of +/- 1.

    Solution:

    a) 21.21 mm

    b) 21.2 mm

    c) 21 mm

    5.33

    Question: How many types of each atom are in each formula?

    1. (NH4)2SO4
    2. CaCO3
    3. Mg(OH)2
    4. NaHCO3

    What We Know: A chemical formula gives the number of atoms in a compound and the element ratio within a compound.

    What It's Asking For: Determine the number of each atom in the given compounds.

    Strategy: The subscripts after each atom give the number of atoms in the compound. If the subscript is outside of the parenthesis, the subscript is applied to each atom within the parenthesis.

    Solution:

    1. 2 N, 8 H, 1 S, 4 O
    2. 1 Ca, 1 C, 3 O
    3. 1 Mg, 2 O, 2 H
    4. 1 Na, 1 H, 1 C, 3 O
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