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13 February, 07:59

Magnesium has three naturally occurring isotopes (Mg-24, Mg-25, and Mg-26). The atomic mass and natural abundance of Mg-24 are 23.9850amu and 79 %, respectively. The atomic mass and natural abundance of Mg-25 are 24.9858amu and 10 %, respectively. Find the natural abundance of Mg-26. Express your answer using two significant figures. Find the atomic mass of Mg-26. Express your answer using two significant figures.

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Answers (2)
  1. 13 February, 08:04
    0
    The answer to your question is below

    Explanation:

    Data

    Atomic mass Abundance

    Mg - 24 = 23.9850 79%

    Mg - 25 = 24.9858 10%

    Mg - 26=??

    Process

    1. - Find the abundance of Mg-26

    The sum of the abundance of the three isotopes equals 100%

    Abundance Mg-24 + Abundance-Mg-25 + Abundance-26 = 100

    79 + 10 + Abundance-26 = 100

    Abundance Mg-26 = 100 - 89

    Abundance Mg-26 = 11%

    2. - Find the atomic mass of Mg-26, the average atomic mass is 24.31 amu

    Average atomic mass = (abundance) (atomic mass - 24) + (abundance)

    (atomic mass-25) + (abundance) (atomic mass-26)

    24.31 = (0.79) (23.9850) + (0.10) (24.9858) + (Atomic mass-26) (0.11)

    24.31 = 18.94815 + 2.4986 + 0.11 (atomic mass-26)

    24.31 = 21.4342 + 0.11 (atomic mass - 26)

    0.11 (atomic mass-26) = 24.31 - 21.4342

    0.11 (atomic mass-26) = 2.8758

    Atomic mass-26 = 2.8758/0.11

    Atomic mass-26 = 26.1436 amu
  2. 13 February, 08:16
    0
    The atomic mass of Mg-26 is 25.9843 amu and has a natural abundance of 11%

    Explanation:

    Step 1: Data given

    Isotopes of Magnesium:

    ⇒ Mg - 24 = 23.9850 amu ⇒ 79 %

    ⇒ Mg - 25 = 24.9858 amu ⇒ 10%

    ⇒ Mg - 26 = ? amu ⇒ 11 %

    atomic mass of magnesium = 24.305 amu

    0.79 * 23.9850 + 0.10 * 24.9858 + 0.11 * x = 24.305

    18.94815 + 2.49858 + 0.11x = 24.305

    0.11x = 2.85827

    x = 25.9843 amu

    The atomic mass of Mg-26 is 25.9843 amu and has a natural abundance of 11%
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