Otis watches a cooking show on making mayonnaise. The chef dissolves salt and sugar in vinegar. She mixes in an egg yolk, and th
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<u>Answer:</u> The average atomic mass of element Zinc is 65.40 amu.
<u>Explanation:</u>
Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.
Formula used to calculate average atomic mass follows:
.....(1)
- <u>For
isotope:</u>
Mass of isotope = 63.929 amu
Percentage abundance of isotope = 48.63 %
Fractional abundance of isotope = 0.4863
- <u>For
isotope:</u>
Mass of isotope = 65.926 amu
Percentage abundance of isotope = 27.90 %
Fractional abundance of isotope = 0.2790
- <u>For
isotope:</u>
Mass of isotope = 66.927 amu
Percentage abundance of isotope = 4.10 %
Fractional abundance of isotope = 0.0410
- <u>For
isotope:</u>
Mass of isotope = 67.925 amu
Percentage abundance of isotope = 18.75 %
Fractional abundance of isotope = 0.1875
- <u>For
isotope:</u>
Mass of isotope = 69.925 amu
Percentage abundance of isotope = 0.62 %
Fractional abundance of isotope = 0.0062
Putting values in equation 1, we get:
Hence, the average atomic mass of element Zinc is 65.40 amu.
In a sample of pure calcium fluoride of mass 15.0 g, 7.70 g of calcium is present. First convert the mass into number of moles as follows:
Here, m is mass and M is molar mass.
Molar mass of Ca is 40 g/mol, putting the values,
Similarly, molar mass of is 78.07 g/mol thus, number of moles will be:
.
Thus, 0.1921 mol of have 0.1925 mol of Ca, or 1 mole of
will have approximately 1 mole of Ca.
Now, mass of Ca needs to be calculated in 45.0 g of . Converting mass into number of moles first,
Thus, number of moles of Ca will also be 0.5764 mol, converting number of moles into mass,
Therefore, mass of Ca will be 23.06 g.