Isotopic Abundance



Isotopic Abundance

1. The atomic weight of gallium is 69.72 g/mol. The masses of the naturally occurring isotopes are 68.9257 g/mol for Gallium – 69 and 70.9249 g/mol for Gallium – 71. Calculate the percent abundance of each isotope.

2. The atomic weight of copper is 63.546 g/mol. The two naturally occurring isotopes of copper have the following masses: Copper – 63 has a mass of 62.9298 g/mol and Copper – 65 has a mass of 64.9278 g/mol. Calculate the percent abundance of each of the isotopes.

3. Silver consists of two naturally occurring isotopes: Silver – 107 which has a mass of 106.90509 g/mol and Silver – 109 which has a mass of 108.682 g/mol. Determine the percent abundance of each isotope in naturally occurring silver.

4. Antimony, one of the elements known to the ancient alchemists, has two stable isotopes: Antimony – 121 with a mass of 120.90 g/mol and Antimony – 123 with a mass of 122.90 g/mol. Calculate the percent abundances of the two isotopes.

5. The element lanthanum has two stable isotopes, Lanthanum – 138 has a mass of 137.9071 g/mol and Lanthanum – 139 has an atomic mass of 138.9063 g/mol. From the atomic mass of La, 138.9, calculate the percent abundance of each of the isotopes.

6. The atomic mass of Lithium, according to the periodic table is 6.941 g/mol. Lithium has two natural isotopes with masses of 6.10512 g/mol and 7.01600 g/mol. Calculate the percent abundance of each of the isotopes.

7. Rubidium has two naturally occurring isotopes: Rubidium – 85 with a mass of 84.9118 g/mol and Rubidium – 87 with a mass of 86.9092 g/mol. The atomic mass of Rubidium is 85.4678 g/mol. Calculate the isotopic abundance of each.

8. Bromine has two naturally occurring isotopes: Bromine 81 with a mass of 80.9163 and Bromine – 79 with a mass of 79.1084 g/mol. If the atomic mass of bromine is 79.904 g/mol, calculate the percent abundance of each of the isotopes.

9. An element has two naturally occurring isotopes. Isotope 1 has a mass of 120.9038 g/mol and isotope 2 has a mass of 122.9042 g/mol. If the average atomic mass is 121.4583 g/mol, what is the percent abundance of each isotope?

10. Naturally occurring chlorine is a mixture of chlorine – 35 and chlorine 37. According to your periodic table, the mass of chlorine is 35.45 g/mol. What is the percent abundance of each of the isotopes?

11. Naturally occurring bromine is a mixture of bromine – 79 and bromine – 81. According to the periodic table, the mass of bromine is 79.90 g/mol. Calculate the percent abundance of each isotope.

12. The element Mars has an atomic weight of 46.80 g/mol. It has two isotopes: Mars – 46 with a mass of 45.950 g/mol and Mars – 48 with a mass of 48.145 g/mol. Calculate the percent abundance of each isotope.

13. The element Demos has an atomic weight of 66.7 g/mol. It has two isotopes: Demos – 66 with a mass of 65.895 g/mol and Demos 67 with a mass of 66.952 g/mol. Calculate the percent abundance of each isotope.

14. The element Phobos has an atomic weight of 264.35 g/mol. It has two isotopes: Phobos – 264 with a mass of 263.85 g/mol and Phobos – 266 with a mass of 265.824 g/mol. Calculate the percent abundance of each isotope.

15. The element Luna has an atomic weight of 28.15 g/mol. Luna – 28 has a mass of 27.745 g/mol and Luna – 29 has a mass of 29.145 g/mol. Calculate the percent abundance of each isotope.

16. The element Io has an atomic weight of 64.45 g/mol. It has two isotopes: Io – 63 with a mass of 63.245 g/mol and Io – 65 with a mass of 65.012 g/mol. Calculate the percent abundance of each isotope.

17. The element Titan has an atomic weight of 124.67 g/mol. It has two isotopes: Titan – 124 with a mass of 123.842 g/mol and Titan – 125 with a mass of 124.952 g/mol. Calculate the percent abundance of each isotope.

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